Difference between revisions of "ZFS as Root Filesystem"

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{{warning|This page is unofficial. ZFS as root filesystem is not supported under Funtoo Linux, mainly because it has limited benefit. ZFS is still supported but boot on a non-ZFS filesystem first. See [[ZFS]].}}
 +
 
== Introduction ==
 
== Introduction ==
  
This tutorial will show you how to install Funtoo on ZFS (rootfs). This tutorial is meant to be an "overlay" over the [[Funtoo_Linux_Installation|Regular Funtoo Installation]]. Follow the normal installation and only use this guide for steps 2, 3, and 8.
+
This wiki article will show you how to install Funtoo on ZFS (rootfs).
 
 
=== Introduction to ZFS ===
 
 
 
Since ZFS is a new technology for Linux, it can be helpful to understand some of its benefits, particularly in comparison to BTRFS, another popular next-generation Linux filesystem:
 
 
 
* On Linux, the ZFS code can be updated independently of the kernel to obtain the latest fixes. btrfs is exclusive to Linux and you need to build the latest kernel sources to get the latest fixes.
 
 
 
* ZFS is supported on multiple platforms. The platforms with the best support are Solaris, FreeBSD and Linux. Other platforms with varying degrees of support are NetBSD, Mac OS X and Windows. btrfs is exclusive to Linux.
 
 
 
* ZFS has the Adaptive Replacement Cache replacement algorithm while btrfs uses the Linux kernel's Last Recently Used replacement algorithm. The former often has an overwhelmingly superior hit rate, which means fewer disk accesses.
 
 
 
* ZFS has the ZFS Intent Log and SLOG devices, which accelerates small synchronous write performance.
 
 
 
* ZFS handles internal fragmentation gracefully, such that you can fill it until 100%. Internal fragmentation in btrfs can make btrfs think it is full at 10%. Btrfs has no automatic rebalancing code, so it requires a manual rebalance to correct it.
 
 
 
* ZFS has raidz, which is like RAID 5/6 (or a hypothetical RAID 7 that supports 3 parity disks), except it does not suffer from the RAID write hole issue thanks to its use of CoW and a variable stripe size. btrfs gained integrated RAID 5/6 functionality in Linux 3.9. However, its implementation uses a stripe cache that can only partially mitigate the effect of the RAID write hole.
 
 
 
* ZFS send/receive implementation supports incremental update when doing backups. btrfs' send/receive implementation requires sending the entire snapshot.
 
 
 
* ZFS supports data deduplication, which is a memory hog and only works well for specialized workloads. btrfs has no equivalent.
 
 
 
* ZFS datasets have a hierarchical namespace while btrfs subvolumes have a flat namespace.
 
 
 
* ZFS has the ability to create virtual block devices called zvols in its namespace. btrfs has no equivalent and must rely on the loop device for this functionality, which is cumbersome.
 
 
 
The only area where btrfs is ahead of ZFS is in the area of small file
 
efficiency. btrfs supports a feature called block suballocation, which
 
enables it to store small files far more efficiently than ZFS. It is
 
possible to use another filesystem (e.g. reiserfs) on top of a ZFS zvol
 
to obtain similar benefits (with arguably better data integrity) when
 
dealing with many small files (e.g. the portage tree).
 
 
 
For a quick tour of ZFS and have a big picture of its common operations you can consult the page [[ZFS Fun]].
 
 
 
=== Disclaimers ===
 
 
 
{{fancywarning|This guide is a work in progress. Expect some quirks.
 
 
 
Today is 2015-05-12. ZFS has undertaken an upgrade - from 0.6.3 to 0.6.4. Please ensure that you use a RescueCD with ZFS 0.6.3. At present date grub 2.02 is not able to deal with those new ZFS parameters. If you want to use ZFS 0.6.4 for pool creation, you should use the compatability mode.  
 
  
You should upgrade an existing pool only when grub is able to deal with - in a future version ... If not, you will not be able to boot into your system, and no rollback will help!
+
== Prerequisites ==
  
Please inform yourself!}}
+
{{fancyimportant|''ZFS is designed for 64-bit systems. We only recommend and support 64-bit platforms and installations!''}}
 +
{{fancywarning|''ZFS v07.5 (latest in ports as of 18 Jan 2018) is compatible with kernel versions 2.6.32 - 4.14''}}
 +
{{fancywarning|''The guide is under rewrite''}}
 +
It is recommended to give the entire disk to ZFS. As such, this guide will only show how to install ZFS on the whole disk, using legacy boot. Installing on UEFI requires a separate partition for /boot, formatted as FAT32, and is out of the scope of this guide, even though installation on UEFI is certainly possible. Also, this guide will not cover anything related to encryption (native encryption is available: https://github.com/zfsonlinux/zfs/commit/b52563034230b35f0562b6f40ad1a00f02bd9a05).
  
{{fancyimportant|'''Since ZFS was really designed for 64 bit systems, we are only recommending and supporting 64 bit platforms and installations. We will not be supporting 32 bit platforms'''!}}
+
=== Downloading the ISO (With ZFS) ===
 
+
In order to install Funtoo on ZFS, you will need an environment, such as live media, that provides the ZFS tools. This guide will utilize the Ubuntu Desktop 16.04 (live) DVD for amd64.
== Downloading the ISO (With ZFS) ==
+
* Download from '''[https://build.funtoo.org/distfiles/ubuntu-17.10.1-desktop-amd64.iso]'''
In order for us to install Funtoo on ZFS, you will need an environment that already provides the ZFS tools. Therefore we will download a customized version of System Rescue CD with ZFS included.
 
 
 
<pre>
 
Name: sysresccd-4.2.0_zfs_0.6.2.iso  (545 MB)
 
Release Date: 2014-02-25
 
md5sum 01f4e6929247d54db77ab7be4d156d85
 
</pre>
 
 
 
 
 
'''[http://ftp.osuosl.org/pub/funtoo/distfiles/sysresccd/ Download System Rescue CD with ZFS]'''<br />
 
  
 
== Creating a bootable USB from ISO (From a Linux Environment) ==
 
== Creating a bootable USB from ISO (From a Linux Environment) ==
 
After you download the iso, you can do the following steps to create a bootable USB:
 
After you download the iso, you can do the following steps to create a bootable USB:
 +
{{note|The size of the iso is approximately 1.5 GB.}}
 +
Insert your blank USB media into a USB port. Then, inspect the kernel ring buffer with {{c|dmesg}} to identify the device name of your USB storage.
 +
{{console|title=dmesg|body=
 +
[  +5.533491] usb 6-2: new SuperSpeed USB device number 4 using xhci_hcd
 +
[  +0.022995] usb 6-2: New USB device found, idVendor=1b1c, idProduct=1a0c
 +
[  +0.000006] usb 6-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
 +
[  +0.000003] usb 6-2: Product: Voyager Mini 3.0
 +
[  +0.000003] usb 6-2: Manufacturer: Corsair
 +
[  +0.000002] usb 6-2: SerialNumber: 0123456789ABCDEF
 +
[  +0.001095] usb-storage 6-2:1.0: USB Mass Storage device detected
 +
[  +0.000080] scsi host15: usb-storage 6-2:1.0
 +
[  +1.000772] scsi 15:0:0:0: Direct-Access    Corsair  Voyager Mini 3.0 PMAP PQ: 0 ANSI: 6
 +
[  +0.000615] sd 15:0:0:0: Attached scsi generic sg6 type 0
 +
[  +0.000110] sd 15:0:0:0: [sdg] 60566016 512-byte logical blocks: (31.0 GB/28.9 GiB)
 +
[  +0.000209] sd 15:0:0:0: [sdg] Write Protect is off
 +
[  +0.000004] sd 15:0:0:0: [sdg] Mode Sense: 2b 00 00 08
 +
[  +0.000227] sd 15:0:0:0: [sdg] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
 +
[  +0.359532] sd 15:0:0:0: [sdg] Attached SCSI removable disk
 +
}}
 +
In this example, {{c|[sdg]}} indicates that the device is {{c|/dev/sdg}}.
  
<console>
+
A quick and easy way to create a bootable USB is to write the ISO data to the USB device using {{c|dd}}.
Make a temporary directory
+
{{console|body=
# ##i##mkdir /tmp/loop
+
###i## dd if=/path/to/iso/ubuntu-16.04-desktop-amd64.iso of=/dev/sdg bs=4K
 +
}}
  
Mount the iso
+
Once this has completed, remove and use this USB to boot the target system that will receive Funtoo Linux.
# ##i##mount -o ro,loop /root/sysresccd-4.2.0_zfs_0.6.2.iso /tmp/loop
 
 
 
Run the usb installer
 
# ##i##/tmp/loop/usb_inst.sh
 
</console>
 
 
 
That should be all you need to do to get your flash drive working.
 
  
 
== Booting the ISO ==
 
== Booting the ISO ==
 +
Using legacy (BIOS) boot mode, boot the ISO and allow Ubuntu to load the graphical environment. You will be presented with a "Welcome" dialog (titled ''Install (as superuser)''). Select the option "Try Ubuntu".
  
{{fancywarning|'''When booting into the ISO, Make sure that you select the "Alternate 64 bit kernel (altker64)". The ZFS modules have been built specifically for this kernel rather than the standard kernel. If you select a different kernel, you will get a fail to load module stack error message.'''}}
+
Once the desktop has loaded, open the search bar by left-clicking on the top-left icon ("Search your computer"). Pressing Alt+F1 should also open this search bar. Search for and open the Terminal application.
  
== Creating partitions ==
+
In the terminal, issue the following commands to install and load the required ZFS module.
There are two ways to partition your disk: You can use your entire drive and let ZFS automatically partition it for you, or you can do it manually.
 
  
We will be showing you how to partition it '''manually''' because if you partition it manually you get to create your own layout, you get to have your own separate /boot partition (Which is nice since not every bootloader supports booting from ZFS pools), and you get to boot into RAID10, RAID5 (RAIDZ) pools and any other layouts due to you having a separate /boot partition.
+
{{console|body=
 +
ubuntu@ubuntu:~$##i## sudo -i
 +
root@ubuntu:~###i## apt-add-repository universe
 +
root@ubuntu:~###i## apt update
 +
root@ubuntu:~###i## apt install --yes debootstrap gdisk zfs-initramfs
 +
}}
  
==== gdisk (GPT Style) ====
+
Verify that the ZFS kernel module has loaded.
 
+
{{console|body=
'''A Fresh Start''':
+
root@ubuntu:~# ##i## dmesg {{!}} grep ZFS
 +
[  377.595348] ##r##ZFS##!r##: Loaded module v0.6.5.6-0ubuntu10, ##r##ZFS##!r## pool version 5000, ##r##ZFS##!r## filesystem version 5
 +
}}
  
First lets make sure that the disk is completely wiped from any previous disk labels and partitions.
+
== Drive Partitions ==
We will also assume that <tt>/dev/sda</tt> is the target drive.<br />
+
We are letting ZFS automatically partition the drive. This is ideal for our example using a single disk and legacy (BIOS) boot.
  
 +
=== Creating of pool ===
 +
Create a ZFS Storage Pool using a single whole disk.
 
<console>
 
<console>
# ##i##sgdisk -Z /dev/sda
+
root@ubuntu:~###i## zpool create -d -o feature@async_destroy=enabled -o feature@empty_bpobj=enabled -o feature@lz4_compress=enabled -o feature@spacemap_histogram=enabled -o feature@enabled_txg=enabled -o feature@extensible_dataset=enabled -o feature@bookmarks=enabled -f -o ashift=12 -o cachefile=/tmp/zpool.cache -O normalization=formD -O atime=off -O xattr=sa -O compression=lz4 -m none -R /mnt/funtoo rpool /dev/disk/by-id/foo
 
</console>
 
</console>
 +
The options used here are
 +
{{TableStart}}
 +
{{2ColHead|option|description}}
 +
{{2Col|{{c|create}}|Use {{c|zpool}} to create a ZFS Storage Pool.}}
 +
{{2Col|{{c|-d}}|Required. Disables enabling all availabe zfs features. This is needed as the GRUB bootloader currently can't handle all advanced zfs features, not specifying this flag on pool creation (or running 'zpool upgrade' on the pool at a later point in time) will make the pool incompatible with GRUB.}}
 +
{{2Col|{{c|(multiple) -o feature@<name>{{=}}enabled}}|Explicitely enable all features currently supported by GRUB. See 'man zpool-features' for details on their effects.}}
 +
{{2Col|{{c|-f}}|Force the use of the selected disk.}}
 +
{{2Col|{{c|-o ashift{{=}}12}}|Alignment of the pool to underlying hard drive sectors. The recommended value is 12, which corresponds to 2^12 Bytes or 4 KiB. This value is typical for present-day HDD's. Can only be set once at pool creation.}}
 +
{{2Col|{{c|-o cachefile{{=}}/tmp/zpool.cache}}|Create a pool configuration cache and place it in {{f|/tmp}}. This will be required for our Funtoo install.}}
 +
{{2Col|{{c|-O normalization{{=}}formD}}|Recommended. Set the default Unicode (UTF-8) normalization for future filesystems (created within this pool) to 'formD'.}}
 +
{{2Col|{{c|-O atime{{=}}off}}|Recommended. As a default preference, set future filesystems (created within this pool) to not update file access time. Useful if we want to reduce writes to disk (e.g., Solid State Drives). Can cause problems for mailers and other software that rely on file access-time data.}}
 +
{{2Col|{{c|-O xattr{{=}}sa}}|Recommended. As a default preference, set future filesystems (created within this pool) to store extended file attributes in a more efficient manner.}}
 +
{{2Col|{{c|-O compression{{=}}lz4}}|Recommended. As a default preference, set future filesystems (created within this pool) to be compressed using the lz4 algorithm. Useful in general as the runtime cost for compression is neglible on these days while on-disk space still costs money.}}
 +
{{2Col|{{c|-m none}}|Do not set mountpoint for this storage pool. (This guide will address this later).}}
 +
{{2Col|{{c|-R /mnt/funtoo}}|Alternate root directory. Essentially a temporary 'mount point' for our pool.}}
 +
{{2Col|{{c|rpool}}|The name of this ZFS Storage Pool. The pool name is irrelevant. {{c|rpool}} will be used throughout this guide.}}
 +
{{2Col|{{c|/dev/disk/by-id/foo}}|The path to the physical disk. e.g. /dev/disk/by-id/ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF. Known in 'ZFS-speak' as a 'VDEV'.}}
 +
{{TableEnd}}
 +
Please note that the options 'ashift' and 'cachefile' are preceded with a lowercase '-o', while 'normalization' and 'atime' are preceded with an uppercase '-O'.
 +
 +
Without additional options, this will create our storage pool and enable all 'features' available under version 0.6.5.6. The pool will be automatically mounted at the (temporary) location {{f|/mnt/funtoo}}.
  
{{fancywarning|This is a destructive operation and the program will not ask you for confirmation! Make sure you really don't want anything on this disk.}}
+
To confirm the presence of our newly created pool:
 +
{{console|body=
 +
root@ubuntu:~###i## zpool status
 +
  pool: rpool
 +
state: ONLINE
 +
  scan: none requested
 +
config:
  
Now that we have a clean drive, we will create the new layout.
+
NAME                                            STATE    READ WRITE CKSUM
 +
rpool                                            ONLINE      0    0    0
 +
  ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF  ONLINE      0    0    0
  
First open up the application:
+
errors: No known data errors
 +
}}
  
 +
=== Create ZFS Datasets ===
 +
Now, we will create one or more ZFS datasets within our storage pool. These will contain Funtoo Linux.
 +
==== Create the Root file system (Required) ====
 
<console>
 
<console>
# ##i##gdisk /dev/sda
+
# ##i## zfs create -o mountpoint=none -o canmount=off rpool/ROOT
 +
# ##i## zfs create -o mountpoint=/ rpool/ROOT/funtoo
 
</console>
 
</console>
 
+
==== Create optional Datasets====
'''Create Partition 1''' (boot):
+
The following optional datasets are provided as examples. It is up to the user to create their own datasets.
 +
===== Home=====
 
<console>
 
<console>
Command: ##i##n ↵
+
# ##i## zfs create -o mountpoint=/home rpool/HOME
Partition Number: ##i##
 
First sector: ##i##↵
 
Last sector: ##i##+250M ↵
 
Hex Code: ##i##↵
 
</console>
 
 
 
'''Create Partition 2''' (BIOS Boot Partition):
 
<console>Command: ##i##n ↵
 
Partition Number: ##i##↵
 
First sector: ##i##↵
 
Last sector: ##i##+32M ↵
 
Hex Code: ##i##EF02 ↵
 
 
</console>
 
</console>
 
+
=====Build directory=====
'''Create Partition 3''' (ZFS):
 
<console>Command: ##i##n ↵
 
Partition Number: ##i##↵
 
First sector: ##i##↵
 
Last sector: ##i##↵
 
Hex Code: ##i##bf00 ↵
 
 
 
Command: ##i##p ↵
 
 
 
Number  Start (sector)    End (sector)  Size      Code  Name
 
  1            2048          514047  250.0 MiB  8300  Linux filesystem
 
  2          514048          579583  32.0 MiB    EF02  BIOS boot partition
 
  3          579584      1953525134  931.2 GiB  BF00  Solaris root
 
 
 
Command: ##i##w ↵
 
</console>
 
 
 
 
 
=== Format your /boot partition ===
 
 
 
 
<console>
 
<console>
# ##i##mkfs.ext2 -m 1 /dev/sda1
+
# ##i## zfs create -o mountpoint=none -o canmount=off rpool/FUNTOO
 +
# ##i## zfs create -o mountpoint=/var/tmp/portage -o compression=lz4 -o sync=disabled rpool/FUNTOO/build
 
</console>
 
</console>
 +
=====Swap on ZFS=====
 +
With some careful tuning a swap partition can be created on a ZFS 'volume' [https://github.com/zfsonlinux/zfs/wiki/FAQ]. For a 2 GB swapfs:
 +
{{console|body=
 +
# ##i## zfs create -V 2G -b $(getconf PAGESIZE) -o logbias=throughput -o sync=always -o primarycache=metadata rpool/swap
 +
# ##i## mkswap /dev/zvol/rpool/swap
 +
# ##i## swapon /dev/zvol/rpool/swap
 +
}}
 +
Note that swap on ZFS has known stability issues. If the user has decided to use swap, please take following into account:
 +
Always use long <code>/dev/zvol</code> aliases in configuration files. Never use a short <code>/dev/zdX</code> device name.
  
=== Create the zpool ===
+
To confirm the presence of the filesystems that we have created:
We will first create the pool. The pool will be named  <code>tank</code>. Feel free to name your pool as you want.  We will use <code>ashift=12</code> option  which is used for a hard drives with a 4096 sector size.
+
{{console|body=
<console># ##i##  zpool create -f -o ashift=12 -o cachefile=/tmp/zpool.cache -O normalization=formD -m none -R /mnt/funtoo tank /dev/sda3 </console>
+
root@ubuntu:~# ##i##zfs list -t all
 +
NAME                USED  AVAIL REFER  MOUNTPOINT
 +
rpool              660K  19.3G    96K  none
 +
rpool/HOME          96K  19.3G    96K  /mnt/funtoo/home
 +
rpool/ROOT          192K  19.3G    96K  none
 +
rpool/ROOT/funtoo   96K  19.3G    96K  /mnt/funtoo
 +
}}
  
=== Create the zfs datasets ===
+
===Make the root filesystem bootable===
We will now create some datasets. For this installation, we will create a small but future proof amount of datasets. We will have a dataset for the OS (/), and your swap. We will also show you how to create some optional datasets: <code>/home</code>, <code>/usr/src</code>, and <code>/usr/portage</code>.  Notice, datasets are examples only and not strictly required.
+
{{important|Do not skip this!}}
 +
When booting from ZFS, you must specify a boot device and a root file system within the pool that was identified by the boot deviceBy default, the dataset selected for booting is the one identified by the pool's <code>bootfs</code> property.
  
 
<console>
 
<console>
Create some empty containers for organization purposes, and make the dataset that will hold /
+
# ##i##zpool set bootfs=rpool/ROOT/funtoo rpool
# ##i## zfs create -p tank/funtoo
 
# ##i## zfs create -o mountpoint=/ tank/funtoo/root
 
 
 
Optional, Create swap
 
# ##i## zfs create tank/swap -V 2G -b 4K
 
# ##i## mkswap /dev/tank/swap
 
# ##i## swapon /dev/tank/swap
 
 
 
Optional, but recommended datasets: /home
 
# ##i## zfs create -o mountpoint=/home tank/funtoo/home
 
 
 
Optional datasets: /usr/src, /usr/portage/{distfiles,packages}
 
# ##i## zfs create -o mountpoint=/usr/src tank/funtoo/src
 
# ##i## zfs create -o mountpoint=/usr/portage -o compression=off tank/funtoo/portage
 
# ##i## zfs create -o mountpoint=/usr/portage/distfiles tank/funtoo/portage/distfiles
 
# ##i## zfs create -o mountpoint=/usr/portage/packages tank/funtoo/portage/packages
 
 
</console>
 
</console>
  
 
== Installing Funtoo ==
 
== Installing Funtoo ==
 +
Now that the initial ZFS pool and datasets have been created, we can unpack the stage 3 tarball and proceed with basic system installation. This part does not differ much from a regular Funtoo Linux installation (https://www.funtoo.org/Install#Installing_the_Stage_3_tarball). We recommend using <code>funtoo-current</code> stages for ZFS.
  
=== Pre-Chroot ===
+
{{console|body=
 
+
# ##i## cd /mnt/funtoo
<console>
+
# ##i## wget https://build.funtoo.org/funtoo-current/x86-64bit/generic_64/stage3-latest.tar.xz
Go into the directory that you will chroot into
+
}}
# ##i##cd /mnt/funtoo
 
  
Make a boot folder and mount your boot drive
+
Extract the contents with the following command. If the user is using an arch-optimized stage 3 tarball, substitute in the actual filename.
# ##i##mkdir boot
 
# ##i##mount /dev/sda1 boot
 
</console>
 
  
[[Funtoo_Linux_Installation|Now download and extract the Funtoo stage3 ...]]
+
{{console|body=
 +
# ##i## tar xpf stage3-latest.tar.xz
 +
}}
  
 +
Now, we need to create a chroot environment:
  
{{fancynote|It is trully recommended to use the current version and generic64. That reduces the risk of a broken build.
+
{{console|body=
 
+
# ##i##cd /mnt/funtoo
After successfull ZFS installation and successfull first boot, the kernel may be changed using the <code> eselect profile set ... </code> command. If you create a snapshot before, you may allways come back to your previous installation, with some simple steps ... (rollback your pool and in the worst case configure and install the bootloader again)}}
 
 
 
 
 
 
 
Once you've extracted the stage3, do a few more preparations and chroot into your new funtoo environment:
 
 
 
<console>
 
Bind the kernel related directories
 
 
# ##i##mount -t proc none proc
 
# ##i##mount -t proc none proc
 +
# ##i##mount --rbind /sys sys
 
# ##i##mount --rbind /dev dev
 
# ##i##mount --rbind /dev dev
# ##i##mount --rbind /sys sys
+
}}
 +
 
 +
An important step is to copy the ZFS cache into the chroot. The ZFS cache was created when <code>rpool</code> was created with the <code>-o cachefile=/tmp/zpool.cache</code> flag.
 +
{{console|body=
 +
# ##i##mkdir -p /mnt/funtoo/etc/zfs
 +
# ##i##cp /tmp/zpool.cache /mnt/funtoo/etc/zfs/zpool.cache
 +
}}
  
Copy network settings
+
You will also want to copy over {{f|resolv.conf}} in order to have proper resolution of Internet hostnames from inside the chroot:
# ##i##cp -f /etc/resolv.conf etc
 
  
Make the zfs folder in 'etc' and copy your zpool.cache
+
{{console|body=
# ##i##mkdir etc/zfs
+
# ##i##cp /etc/resolv.conf /mnt/funtoo/etc/
# ##i##cp /tmp/zpool.cache etc/zfs
+
}}
 +
We are now ready to <code>chroot</code>.
  
Chroot into Funtoo
+
{{console|body=
# ##i##env -i HOME=/root TERM=$TERM chroot . bash -l
+
# ##i##chroot /mnt/funtoo /bin/bash
</console>
+
# ##i##export PS1="(chroot) $PS1"; cd
 +
}}
  
{{fancynote|How to create zpool.cache file?}}
+
==Configuring your system==
If no <code>zpool.cache</code> file is available, the following command will create one:
+
Configure your system according to the main [[Install|install guide]]. During startup, ZFS filesystems will be mounted '''without''' needing any entries in {{f|/etc/fstab}}. Comment out all entries in {{f|/etc/fstab}} except for partitions such as CD-ROMs, tmpfs, etc., if used.
<console>
 
# ##i##zpool set cachefile=/etc/zfs/zpool.cache tank
 
</console>
 
  
{{:Install/PortageTree}}
+
If you created a '''swap''' volume earlier, add an appropriate entry to {{f|/etc/fstab}}.
 +
{{console|body=
 +
# ##i## echo /dev/zvol/rpool/swap none swap defaults 0 0 >> /etc/fstab
 +
}}
 +
Note that swap on ZFS is unstable. If you decide to use swap, please take following into account:
 +
always use long <code>/dev/zvol</code> aliases in configuration files. Never use a short <code>/dev/zdX</code> device name.
  
=== Add filesystems to /etc/fstab ===
+
Next, update the portage tree:
 +
{{console|body=
 +
###i## ego sync
 +
###i## env-update
 +
###i## source /etc/profile
 +
}}
  
Before we continue to compile and or install our kernel in the next step, we will edit the <code>/etc/fstab</code> file because if we decide to install our kernel through portage, portage will need to know where our <code>/boot</code> is, so that it can place the files in there.
+
== Installing ZFS userspace and bootloader==
 +
=== Installing the ZFS userspace tools and kernel modules ===
  
Edit <code>/etc/fstab</code>:
+
Install the ZFS packages and sync the portage tree, if required:
 +
{{console|body=
 +
###i## ego sync
 +
###i## emerge --ask sys-fs/zfs
 +
}}
  
{{file|name=/etc/fstab|desc= |body=
+
Once it has successfully merged, add the following services to the boot runlevel of OpenRC:
# <fs>                  <mountpoint>    <type>          <opts>          <dump/pass>
+
{{console|body=
 +
###i## rc-update add zfs-import boot
 +
###i## rc-update add zfs-mount boot
 +
}}
 +
Add another two services to the default runlevel:
 +
{{console|body=
 +
###i## rc-update add zfs-share default
 +
###i## rc-update add zfs-zed default
 +
}}
  
/dev/sda1              /boot          ext2            defaults        0 2
+
=== Create a ZFS-friendly initramfs ===
 +
The Funtoo stage3 includes a linux kernel and initramfs. The initramfs is designed to mount and start Funtoo Linux on a variety of file systems. The initramfs contained within the stage3 will '''not''' mount and start Funtoo in our ZFS storage pool. We must create an updated 'ZFS-friendly' initramfs.
  
# If you set up a swap partition, you will have to add this line as well
+
Optional: Update to the latest {{package|sys-kernel/genkernel}}:
/dev/zvol/tank/swap    none            swap            defaults        0 0
+
{{console|body=
 +
# ##i##emerge --oneshot sys-kernel/genkernel
 
}}
 
}}
  
== Building kernel, initramfs and grub to work with zfs==
+
Use {{c|genkernel}} to create an initramfs capable of mounting our ZFS Storage Pool via the {{c|--zfs}} switch. Adjust {{c|--makeopts}} according to the number of available threads:
=== Install genkernel and initial kernel build ===
+
{{console|body=
 +
# ##i##genkernel initramfs --no-clean --no-mountboot --makeopts=-j4 --kernel-config=/usr/src/linux/.config --zfs
 +
##g##* Funtoo Linux Genkernel; Version 3.4.40.11-funtoo##!g##
 +
##g##*##!g## Running with options: initramfs --no-clean --no-mountboot --makeopts=-j4 --kernel-config=/usr/src/linux/.config --zfs
  
We need to build a genkernel initially:
+
##g##*##!g## Linux Kernel 4.5.2-1 for x86_64...
<console>
+
##g##*##!g## .. with config file /usr/src/linux-debian-sources-4.5.2/.config
# ##i##emerge genkernel
+
##g##*##!g## busybox: >> Using cache
 +
##g##*##!g## initramfs: >> Initializing...
 +
##g##*##!g##        >> Appending base_layout cpio data...
 +
##g##*##!g##        >> Appending auxilary cpio data...
 +
##g##*##!g##        >> Copying keymaps
 +
##g##*##!g##        >> Appending busybox cpio data...
 +
##g##*##!g##        >> Appending modules cpio data...
 +
##g##*##!g##        >> Appending zfs cpio data...
 +
cp: cannot stat ‘/etc/zfs/zdev.conf’: No such file or directory
 +
##y##*##!y## Could not copy file /etc/zfs/zdev.conf for ZFS
 +
##g##*##!g##        >> Appending blkid cpio data...
 +
##g##*##!g##        >> Appending modprobed cpio data...
 +
##g##*##!g##        >> Compressing cpio data (.xz)...
  
Build initial kernel (required for checks in sys-kernel/spl and sys-fs/zfs):
+
##y##*##!y## WARNING... WARNING... WARNING...
# ##i##genkernel kernel --no-clean --no-mountboot
+
##y##*##!y## Additional kernel cmdline arguments that *may* be required to boot properly...
 +
##y##*##!y## add "dozfs" for ZFS volume management support
 +
##y##*##!y## add either "real_root=ZFS" (bootfs autodetection) or "real_root=ZFS=<dataset>" to boot from a ZFS dataset
  
</console>
+
##g##*##!g## Do NOT report kernel bugs as genkernel bugs unless your bug
 +
##g##*##!g## is about the default genkernel configuration...
 +
##g##*##!g##
 +
##g##*##!g## Make sure you have the latest ~arch genkernel before reporting bugs.
 +
}}
  
=== Installing the ZFS userspace tools and kernel modules ===
+
Confirm the presence of the new initramfs:
Emerge {{Package|sys-fs/zfs}}. This package will bring in {{Package|sys-kernel/spl}}, and {{Package|sys-fs/zfs-kmod}} as its dependencies:
+
{{console|body=
 +
###i## ls /boot/*genkernel*
 +
/boot/initramfs-genkernel-x86_64-4.5.2-1
 +
}}
  
<console>
+
Grub expects the initramfs filename to be of the form: <code>initramfs-${KNAME}-${ARCH}-${KV}</code>. This guide assumes the usage of debian-sources. Tailor it to your specific kernel name, platform, and kernel version. Forgetting to rename <code>initramfs-genkernel</code> to <code>initramfs-debian-sources</code> will render the system unbootable.
# ##i##emerge zfs
+
{{console|body=
</console>
+
###i## cd /boot
 
+
###i## mv initramfs-genkernel-x86_64-4.5.2-1 initramfs-debian-sources-x86_64-4.5.2-1
Check to make sure that the zfs tools are working. The <code>zpool.cache</code> file that you copied before should be displayed.
+
###i## ls /boot/*initramfs*
 +
/boot/initramfs-debian-sources-x86_64-4.5.2-1
 +
}}
  
 +
=== Installing GRUB 2  ===
 +
GRUB 2 must be built with support for ZFS Storage Pools on a single disk. This is achieved using the 'libzfs' USE flag.
 
<console>
 
<console>
# ##i##zpool status
+
# ##i##echo "sys-boot/grub libzfs" >> /etc/portage/package.use
# ##i##zfs list
 
 
</console>
 
</console>
  
{{fancynote|If /etc/mtab is missing, these two commands will complaine.
+
{{Note|If you have defined GRUB_PLATFORMS in your {{f|/etc/portage/make.conf}}, please ensure that it includes 'pc': e.g. GRUB_PLATFORMS{{=}}"efi-64 pc".
In that case solve that with:
 
<console>
 
# ##i##grep -v rootfs /proc/mounts > /etc/mtab
 
</console>}}
 
  
Add the zfs tools to openrc.
+
This is required for booting in BIOS (non-UEFI) mode, as described in this guide.}}
<console># ##i##rc-update add zfs boot</console>
 
  
If everything worked, continue.
+
Now, install GRUB:
 
 
=== Install GRUB 2  ===
 
 
 
Install grub2:
 
 
<console>
 
<console>
# ##i##echo "sys-boot/grub libzfs -truetype" >> /etc/portage/package.use
 
 
# ##i##emerge grub
 
# ##i##emerge grub
 
</console>
 
</console>
  
Now install grub to the drive itself (not a partition):
+
=== Configuring the Bootloader ===
<console>
+
When {{c|zpool}} created our storage pool (rpool), it created partitions under a GPT scheme. In order to boot Funtoo Linux on a GPT partion under legacy (BIOS) boot, <code>sys-boot/grub</code> requires a small partition, called a BIOS boot partition. By design, ZFS ({{c|zpool}}) left a very small unpartitioned space at the beginning of the disk. We will use <code>sgdisk</code>, which is part of <code>sys-apps/gptfdisk</code>, to format this free space into a BIOS boot partition.
# ##i##grub-install /dev/sda
 
</console>
 
  
=== Initial kernel build ===
+
{{console|body=
Build now kernel and initramfs with --zfs
+
###i## sgdisk -a1 -n2:48:2047 -t2:EF02 -c2:"BIOS boot partition" /dev/disk/by-id/ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF
<console>
+
}}
# ##i##genkernel all --zfs --no-clean --no-mountboot --callback="emerge @module-rebuild"
 
</console>
 
  
=== Configuring the Bootloader ===
+
To avoid problems with GRUB, use {{c|partx}} to refresh the list of partitions that are 'seen' by the kernel. Do this for each drive (/dev/sda, /dev/sdb, etc.).
 +
{{console|body=
 +
###i## partx -u /dev/sda
 +
}}
  
Using the genkernel you must add 'real_root=ZFS=<root>' and 'dozfs' to your params.
+
A quick check to verify that GRUB 2 sees/supports ZFS:
Edit  <code>/etc/boot.conf</code>:
+
{{console|body=
 +
###i## touch /etc/mtab
 +
###i## grub-probe /
 +
zfs
 +
}}
  
{{file|name=/etc/boot.conf|desc= |body=
+
Installing GRUB2 to disk is as easy as:
"Funtoo ZFS" {
+
{{console|body=
        kernel kernel[-v]
+
###i## grub-install /dev/disk/by-id/ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF
        initrd initramfs-genkernel-x86_64[-v]
+
Installing for i386-pc platform.
        params real_root=ZFS=tank/funtoo/root
+
Installation finished. No error reported.
        params += dozfs=force
 
}
 
 
}}
 
}}
  
The command <code>boot-update</code> should take care of grub configuration:
+
Now, it's time for us to create grub's configuration file. First, we must edit a few GRUB 2 settings in {{f|/etc/default/grub}}:
 +
{{important|The following is required to boot Funtoo Linux on ZFS!}}
 +
Replace the line
 +
{{file|name=/etc/default/grub|desc=before|body=
 +
#GRUB_CMDLINE_LINUX=""
 +
}}
 +
with
 +
{{file|name=/etc/default/grub|desc=after|body=
 +
GRUB_CMDLINE_LINUX="dozfs real_root=ZFS=rpool/ROOT/funtoo"
 +
}}
  
<console>
+
Now, create GRUB 2 configuration file:
Install boot-update (if it is missing):
+
{{console|body=
###i## emerge boot-update
+
###i## grub-mkconfig -o /boot/grub/grub.cfg
 +
Generating grub configuration file ...
 +
Found linux image: /boot/kernel-debian-sources-x86_64-4.5.2-1
 +
Found initrd image: /boot/initramfs-genkernel-x86_64-4.5.2-1
 +
done
 +
}}
  
Run boot-update to update grub.cfg
+
If grub-mkconfig cannot find the initrd image, manually add initrd to the generated {{c|/boot/grub/grub.cfg}}, below the linux line:
###i## boot-update
+
{{file|name=/boot/grub/grub.cfg|desc=adding initrd below the linux line|body=
</console>
+
echo    'Loading Linux x86_64-4.5.2-1 ...'
 +
linux  /ROOT/funtoo@/boot/kernel-debian-sources-x86_64-4.5.2-1 root=ZFS=rpool/ROOT/funtoo ro dozfs real_root=ZFS
 +
echo    'Loading initial ramdisk ...'
 +
initrd  /ROOT/funtoo@/boot/initramfs-debian-sources-x86_64-4.5.2-1
 +
}}
  
{{fancynote|If <code>boot-update</code>fails, try this:
+
A quick check to verify that the GRUB ZFS module is in place:
<console>
+
{{console|body=
# ##i##grub-mkconfig -o /boot/grub/grub.cfg
+
###i## ls /boot/grub/*/zfs.mod
</console>
+
/boot/grub/i386-pc/zfs.mod
 
}}
 
}}
Now you should have a new installation of the kernel, initramfs and grub which are zfs capable. The configuration files should be updated, and the system should come up during the next reboot.
 
 
{{fancynote|If The <code>luks</code> integration works basically the same way.}}
 
  
 
== Final configuration ==
 
== Final configuration ==
=== Clean up and reboot ===
+
Configure your network according to the main [[Install#Configuring_your_network|installation guide]].
We are almost done, we are just going to clean up, '''set our root password''', and unmount whatever we mounted and get out.
 
  
<console>
+
Set the root password.
Delete the stage3 tarball that you downloaded earlier so it doesn't take up space.
+
{{console|body=
# ##i##cd /
+
(chroot) ###i## passwd
# ##i##rm stage3-latest.tar.xz
+
}}
  
Set your root password
+
Exit the chroot and export your ZFS storage pool.
# ##i##passwd
+
{{console|body=
>> Enter your password, you won't see what you are writing (for security reasons), but it is there!
+
(chroot) ###i## exit
 +
###i## umount -lR {dev,proc,sys}
 +
###i## cd /
 +
###i## zpool export rpool
 +
}}
  
Get out of the chroot environment
+
Restart to boot into Funtoo Linux on a ZFS root!
# ##i##exit
 
  
Unmount all the kernel filesystem stuff and boot (if you have a separate /boot)
+
== After reboot ==
# ##i##umount -l proc dev sys boot
+
===Snapshot===
 +
Take a snapshot of your Funtoo ''at installation''.
 +
{{console|body=
 +
###i## zfs snapshot rpool/ROOT/funtoo@install
 +
}}
 +
The use of snapshots, including sending snapshots as a method of backup, are not covered in this guide. See [[ZFS_Install_Guide#Further_Reading|Further Reading]].
  
Turn off the swap
+
===ZFS Adjustable Replacement Cache (ARC) size===
# ##i##swapoff /dev/zvol/tank/swap
+
The Adjustable Replacement Cache (ARC) is a fundamental part of ZFS. Refer to this [https://pthree.org/2012/12/07/zfs-administration-part-iv-the-adjustable-replacement-cache%20link article] by Aaron Toponce for details on how to set up an ARC.
  
Export the zpool
+
Without configuration, ZFS will use up to 50% of your memory (RAM) for the ARC. It is possible to change this maximum. There are different ways to achieve this on both a temporary and persistent basis. One such way is to create and edit the file {{f|/etc/modprobe.d/zfs.conf}}, which affects the ZFS kernel module.
# ##i##cd /
 
# ##i##zpool export tank
 
  
Reboot
+
{{file|name=/etc/modprobe.d/zfs.conf|desc=set maximum ARC size to 4 GiB|body=
# ##i##reboot
+
options zfs zfs_arc_max=4294967296
</console>
+
}}
 +
where {{c|zfs_arc_max}} is set to a value in Bytes. After configuring this file, re-generate the initramfs. Rebooting will then apply this change.
  
{{fancyimportant|'''Don't forget to set your root password as stated above before exiting chroot and rebooting. If you don't set the root password, you won't be able to log into your new system.'''}}
+
To apply this change immediately without a reboot, issue the command:
 +
{{console|body=
 +
# ##i## echo 4294967296 >> /sys/module/zfs/parameters/zfs_arc_max
 +
}}
  
and that should be enough to get your system to boot on ZFS.
+
Reference: https://wiki.gentoo.org/wiki/ZFS#ARC
  
== After reboot ==
+
===After Kernel or ZFS updates===
 +
The default Funtoo Linux kernel ({{package|sys-kernel/debian-sources}}) does not automatically build a ZFS-capable initramfs. Similarly, the package {{c|sys-fs/zfs}} and its dependencies do not automatically build a ZFS-capable initramfs.
  
=== Forgot to reset password? ===
+
After each kernel update, you must recreate an initramfs. Similarly, {{c|sys-fs/zfs}} updates also require you to regenerate an initramfs. This is especially true for updates to {{c|sys-fs/zfs}} that introduce new storage pool features. Neglecting to update your initramfs will make your system unbootable.
==== System Rescue CD ====
 
If you aren't using bliss-initramfs, then you can reboot back into your sysresccd and reset through there by mounting your drive, chrooting, and then typing passwd.  
 
  
Example:
+
First, rebuild {{c|sys-fs/zfs}}, {{c|sys-fs/zfs-kmod}} and {{c|sys-kernel/spl}}:
<console>
 
# ##i##zpool import -f -R /mnt/funtoo tank
 
# ##i##chroot /mnt/funtoo bash -l
 
# ##i##passwd
 
# ##i##exit
 
# ##i##zpool export -f tank
 
# ##i##reboot
 
</console>
 
  
=== Create initial ZFS Snapshot ===
+
{{console|body=
Continue to set up anything you need in terms of /etc configurations. Once you have everything the way you like it, take a snapshot of your system. You will be using this snapshot to revert back to this state if anything ever happens to your system down the road. The snapshots are cheap, and almost instant.
+
# ##i##emerge --ask --verbose -1 zfs zfs-kmod spl
 +
}}
  
To take the snapshot of your system, type the following:
+
Then, follow the earlier instructions to create a new initramfs:
<console># ##i##zfs snapshot -r tank@install</console>
+
{{console|body=
 +
# ##i##genkernel initramfs --no-clean --no-mountboot --makeopts=-j4 --kernel-config=/usr/src/linux/.config --zfs
 +
# ##i##cd /boot
 +
# ##i##mv initramfs-genkernel-x86_64-4.5.2-1 initramfs-debian-sources-x86_64-4.5.2-1
 +
}}
  
To see if your snapshot was taken, type:
+
Finally, repeat the earlier instructions for generating {{c|/boot/grub/grub.cfg}} and manually adding the new initramfs as initrd to the generated {{c|/boot/grub/grub.cfg}}.
<console># ##i##zfs list -t snapshot</console>
 
  
If your machine ever fails and you need to get back to this state, just type (This will only revert your / dataset while keeping the rest of your data intact):
+
== Further Reading ==
<console># ##i##zfs rollback tank/funtoo/root@install</console>
+
ZFS has many interesting features not covered by this guide.
  
{{fancyimportant|'''For a detailed overview, presentation of ZFS' capabilities, as well as usage examples, please refer to the [[ZFS_Fun|ZFS Fun]] page.'''}}
+
Useful information and instructions can be found in the online reference manuals. See {{c|man zpool}} and {{c|man zfs}}.
  
== Troubleshooting ==
+
Aaron Toponce's Zpool/ZFS Administration Guides - https://pthree.org/2012/12/04/zfs-administration-part-i-vdevs
  
=== Starting from scratch ===
+
ZFS on Linux - http://www.zfsonlinux.org
If your installation has gotten screwed up for whatever reason and you need a fresh restart, you can do the following from sysresccd to start fresh:
 
  
<console>
+
ZFS - Gentoo Wiki - https://wiki.gentoo.org/wiki/ZFS
Destroy the pool and any snapshots and datasets it has
 
# ##i##zpool destroy -R -f tank
 
  
This deletes the files from /dev/sda1 so that even after we zap, recreating the drive in the exact sector
+
== Troubleshooting ==
position and size will not give us access to the old files in this partition.
+
=== Forgot to reset password? ===
# ##i##mkfs.ext2 /dev/sda1
+
You will need to chroot into your Funtoo on ZFS root installation if you forgot to set the root password. Repeat the earlier instructions to load the the live CD/USB, including the installation of ZFS kernel modules.
# ##i##sgdisk -Z /dev/sda
 
</console>
 
  
Now start the guide again :).
+
When the ZFS kernel modules are loaded, your existing ZFS Storage Pool (rpool) will be imported automatically. This will also result in an attempt to mount the various ZFS filesystems that you created. Mounting your root partition (/) will fail since this location is not empty; / is allocated to the live CD/USB distribution!
 +
{{console|body=
 +
###i## zpool status
 +
  pool: rpool
 +
state: ONLINE
 +
  scan: none requested
 +
config:
  
 +
NAME                                            STATE    READ WRITE CKSUM
 +
rpool                                            ONLINE      0    0    0
 +
  ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF  ONLINE      0    0    0
  
=== Starting again reusing the same disk partitions and the same pool ===
+
errors: No known data errors
 +
}}
  
If your installation has gotten screwed up for whatever reason and you want to keep your pole named tank than you should boou into the Rescue CD / USB as done before.
+
To get around this issue, first, manually export the pool.
 +
{{console|body=
 +
###i## zpool export rpool
 +
###i## zpool list
 +
no pools available
 +
}}
  
<console>import the pool reusing all existing datasets:
+
Now, import your storage pool using the following command.
# ##i##zpool import -f -R /mnt/funtoo tank
+
{{console|body=
</console>
+
###i## zpool import -o cachefile=/tmp/zpool.cache -R /mnt/funtoo -d /dev/disk/by-id/ rpool
 
+
}}
Now you should wipe the previous installation off:
+
This will import rpool and place your Funtoo install at {{f|/mnt/funtoo}}. Follow the earlier set of instructions to chroot into your Funtoo Installation on ZFS root.
  
<console>
+
=== Will not mount on first reboot? ===
let's go to our base installation directory:
+
Follow the above instructions on "Forgot to reset password?" to import and mount your storage pool (rpool) and chroot back into your Funtoo environment.
# ##i##cd /mnt/funtoo
 
  
and delete the old installation:
+
Things to check:
# ##i##rm -rf *
+
* Was the ''bootfs'' property of rpool set? Use {{c|zpool get bootfs rpool}} to check
</console>
+
* Was /tmp/zpool.cache copied into /mnt/funtoo/etc/zfs/ prior to chroot and creating the initramfs?
 +
* Was {{c|genkernel initramfs}} run with the --zfs switch and --kernel-config pointing to the correct configuration file?
 +
* Was GRUB installed and configured correctly?
  
Now start the guide again, at "Pre-Chroot"
+
===  rpool is 'busy' on zpool export ===
 +
This happens when swapon is used.
 +
Swap must be turned off to free the pool for export.
  
 +
=== Unable to add universe repository in Ubuntu? ===
 +
See http://askubuntu.com/questions/761592/unable-to-apt-get-dist-upgrade-on-a-persistent-ubuntu-16-04-usb
  
 
[[Category:HOWTO]]
 
[[Category:HOWTO]]
 
[[Category:Filesystems]]
 
[[Category:Filesystems]]
[[Category:Featured]]
 
[[Category:Install]]
 
  
 
__NOTITLE__
 
__NOTITLE__

Latest revision as of 00:52, November 15, 2019

   Warning

This page is unofficial. ZFS as root filesystem is not supported under Funtoo Linux, mainly because it has limited benefit. ZFS is still supported but boot on a non-ZFS filesystem first. See ZFS.

Introduction

This wiki article will show you how to install Funtoo on ZFS (rootfs).

Prerequisites

   Important

ZFS is designed for 64-bit systems. We only recommend and support 64-bit platforms and installations!

   Warning

ZFS v07.5 (latest in ports as of 18 Jan 2018) is compatible with kernel versions 2.6.32 - 4.14

   Warning

The guide is under rewrite

It is recommended to give the entire disk to ZFS. As such, this guide will only show how to install ZFS on the whole disk, using legacy boot. Installing on UEFI requires a separate partition for /boot, formatted as FAT32, and is out of the scope of this guide, even though installation on UEFI is certainly possible. Also, this guide will not cover anything related to encryption (native encryption is available: https://github.com/zfsonlinux/zfs/commit/b52563034230b35f0562b6f40ad1a00f02bd9a05).

Downloading the ISO (With ZFS)

In order to install Funtoo on ZFS, you will need an environment, such as live media, that provides the ZFS tools. This guide will utilize the Ubuntu Desktop 16.04 (live) DVD for amd64.

  • Download from [1]

Creating a bootable USB from ISO (From a Linux Environment)

After you download the iso, you can do the following steps to create a bootable USB:

   Note

The size of the iso is approximately 1.5 GB.

Insert your blank USB media into a USB port. Then, inspect the kernel ring buffer with dmesg to identify the device name of your USB storage.

[  +5.533491] usb 6-2: new SuperSpeed USB device number 4 using xhci_hcd
[  +0.022995] usb 6-2: New USB device found, idVendor=1b1c, idProduct=1a0c
[  +0.000006] usb 6-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  +0.000003] usb 6-2: Product: Voyager Mini 3.0
[  +0.000003] usb 6-2: Manufacturer: Corsair
[  +0.000002] usb 6-2: SerialNumber: 0123456789ABCDEF
[  +0.001095] usb-storage 6-2:1.0: USB Mass Storage device detected
[  +0.000080] scsi host15: usb-storage 6-2:1.0
[  +1.000772] scsi 15:0:0:0: Direct-Access     Corsair  Voyager Mini 3.0 PMAP PQ: 0 ANSI: 6
[  +0.000615] sd 15:0:0:0: Attached scsi generic sg6 type 0
[  +0.000110] sd 15:0:0:0: [sdg] 60566016 512-byte logical blocks: (31.0 GB/28.9 GiB)
[  +0.000209] sd 15:0:0:0: [sdg] Write Protect is off
[  +0.000004] sd 15:0:0:0: [sdg] Mode Sense: 2b 00 00 08
[  +0.000227] sd 15:0:0:0: [sdg] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[  +0.359532] sd 15:0:0:0: [sdg] Attached SCSI removable disk

In this example, [sdg] indicates that the device is /dev/sdg.

A quick and easy way to create a bootable USB is to write the ISO data to the USB device using dd.

root # dd if=/path/to/iso/ubuntu-16.04-desktop-amd64.iso of=/dev/sdg bs=4K

Once this has completed, remove and use this USB to boot the target system that will receive Funtoo Linux.

Booting the ISO

Using legacy (BIOS) boot mode, boot the ISO and allow Ubuntu to load the graphical environment. You will be presented with a "Welcome" dialog (titled Install (as superuser)). Select the option "Try Ubuntu".

Once the desktop has loaded, open the search bar by left-clicking on the top-left icon ("Search your computer"). Pressing Alt+F1 should also open this search bar. Search for and open the Terminal application.

In the terminal, issue the following commands to install and load the required ZFS module.

ubuntu@ubuntu:~$ sudo -i
root@ubuntu:~# apt-add-repository universe
root@ubuntu:~# apt update
root@ubuntu:~# apt install --yes debootstrap gdisk zfs-initramfs

Verify that the ZFS kernel module has loaded.

root@ubuntu:~#  dmesg | grep ZFS
[  377.595348] ZFS: Loaded module v0.6.5.6-0ubuntu10, ZFS pool version 5000, ZFS filesystem version 5

Drive Partitions

We are letting ZFS automatically partition the drive. This is ideal for our example using a single disk and legacy (BIOS) boot.

Creating of pool

Create a ZFS Storage Pool using a single whole disk.

root@ubuntu:~# zpool create -d -o feature@async_destroy=enabled -o feature@empty_bpobj=enabled -o feature@lz4_compress=enabled -o feature@spacemap_histogram=enabled -o feature@enabled_txg=enabled -o feature@extensible_dataset=enabled -o feature@bookmarks=enabled -f -o ashift=12 -o cachefile=/tmp/zpool.cache -O normalization=formD -O atime=off -O xattr=sa -O compression=lz4 -m none -R /mnt/funtoo rpool /dev/disk/by-id/foo

The options used here are

optiondescription
createUse zpool to create a ZFS Storage Pool.
-dRequired. Disables enabling all availabe zfs features. This is needed as the GRUB bootloader currently can't handle all advanced zfs features, not specifying this flag on pool creation (or running 'zpool upgrade' on the pool at a later point in time) will make the pool incompatible with GRUB.
(multiple) -o feature@<name>=enabledExplicitely enable all features currently supported by GRUB. See 'man zpool-features' for details on their effects.
-fForce the use of the selected disk.
-o ashift=12Alignment of the pool to underlying hard drive sectors. The recommended value is 12, which corresponds to 2^12 Bytes or 4 KiB. This value is typical for present-day HDD's. Can only be set once at pool creation.
-o cachefile=/tmp/zpool.cacheCreate a pool configuration cache and place it in /tmp. This will be required for our Funtoo install.
-O normalization=formDRecommended. Set the default Unicode (UTF-8) normalization for future filesystems (created within this pool) to 'formD'.
-O atime=offRecommended. As a default preference, set future filesystems (created within this pool) to not update file access time. Useful if we want to reduce writes to disk (e.g., Solid State Drives). Can cause problems for mailers and other software that rely on file access-time data.
-O xattr=saRecommended. As a default preference, set future filesystems (created within this pool) to store extended file attributes in a more efficient manner.
-O compression=lz4Recommended. As a default preference, set future filesystems (created within this pool) to be compressed using the lz4 algorithm. Useful in general as the runtime cost for compression is neglible on these days while on-disk space still costs money.
-m noneDo not set mountpoint for this storage pool. (This guide will address this later).
-R /mnt/funtooAlternate root directory. Essentially a temporary 'mount point' for our pool.
rpoolThe name of this ZFS Storage Pool. The pool name is irrelevant. rpool will be used throughout this guide.
/dev/disk/by-id/fooThe path to the physical disk. e.g. /dev/disk/by-id/ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF. Known in 'ZFS-speak' as a 'VDEV'.

Please note that the options 'ashift' and 'cachefile' are preceded with a lowercase '-o', while 'normalization' and 'atime' are preceded with an uppercase '-O'.

Without additional options, this will create our storage pool and enable all 'features' available under version 0.6.5.6. The pool will be automatically mounted at the (temporary) location /mnt/funtoo.

To confirm the presence of our newly created pool:

root@ubuntu:~# zpool status
  pool: rpool
 state: ONLINE
  scan: none requested
config:

	NAME                                             STATE     READ WRITE CKSUM
	rpool                                            ONLINE       0     0     0
	  ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF  ONLINE       0     0     0

errors: No known data errors

Create ZFS Datasets

Now, we will create one or more ZFS datasets within our storage pool. These will contain Funtoo Linux.

Create the Root file system (Required)

root #  zfs create -o mountpoint=none -o canmount=off rpool/ROOT
root #  zfs create -o mountpoint=/ rpool/ROOT/funtoo

Create optional Datasets

The following optional datasets are provided as examples. It is up to the user to create their own datasets.

Home
root #  zfs create -o mountpoint=/home rpool/HOME
Build directory
root #  zfs create -o mountpoint=none -o canmount=off rpool/FUNTOO
root #  zfs create -o mountpoint=/var/tmp/portage -o compression=lz4 -o sync=disabled rpool/FUNTOO/build
Swap on ZFS

With some careful tuning a swap partition can be created on a ZFS 'volume' [2]. For a 2 GB swapfs:

root #  zfs create -V 2G -b $(getconf PAGESIZE) -o logbias=throughput -o sync=always -o primarycache=metadata rpool/swap
root #  mkswap /dev/zvol/rpool/swap
root #  swapon /dev/zvol/rpool/swap

Note that swap on ZFS has known stability issues. If the user has decided to use swap, please take following into account: Always use long /dev/zvol aliases in configuration files. Never use a short /dev/zdX device name.

To confirm the presence of the filesystems that we have created:

root@ubuntu:~# zfs list -t all
NAME                USED  AVAIL  REFER  MOUNTPOINT
rpool               660K  19.3G    96K  none
rpool/HOME           96K  19.3G    96K  /mnt/funtoo/home
rpool/ROOT          192K  19.3G    96K  none
rpool/ROOT/funtoo    96K  19.3G    96K  /mnt/funtoo

Make the root filesystem bootable

   Important

Do not skip this!

When booting from ZFS, you must specify a boot device and a root file system within the pool that was identified by the boot device. By default, the dataset selected for booting is the one identified by the pool's bootfs property.

root # zpool set bootfs=rpool/ROOT/funtoo rpool

Installing Funtoo

Now that the initial ZFS pool and datasets have been created, we can unpack the stage 3 tarball and proceed with basic system installation. This part does not differ much from a regular Funtoo Linux installation (https://www.funtoo.org/Install#Installing_the_Stage_3_tarball). We recommend using funtoo-current stages for ZFS.

root #  cd /mnt/funtoo
root #  wget https://build.funtoo.org/funtoo-current/x86-64bit/generic_64/stage3-latest.tar.xz

Extract the contents with the following command. If the user is using an arch-optimized stage 3 tarball, substitute in the actual filename.

root #  tar xpf stage3-latest.tar.xz

Now, we need to create a chroot environment:

root # cd /mnt/funtoo
root # mount -t proc none proc
root # mount --rbind /sys sys
root # mount --rbind /dev dev

An important step is to copy the ZFS cache into the chroot. The ZFS cache was created when rpool was created with the -o cachefile=/tmp/zpool.cache flag.

root # mkdir -p /mnt/funtoo/etc/zfs
root # cp /tmp/zpool.cache /mnt/funtoo/etc/zfs/zpool.cache

You will also want to copy over resolv.conf in order to have proper resolution of Internet hostnames from inside the chroot:

root # cp /etc/resolv.conf /mnt/funtoo/etc/

We are now ready to chroot.

root # chroot /mnt/funtoo /bin/bash
root # export PS1="(chroot) $PS1"; cd

Configuring your system

Configure your system according to the main install guide. During startup, ZFS filesystems will be mounted without needing any entries in /etc/fstab. Comment out all entries in /etc/fstab except for partitions such as CD-ROMs, tmpfs, etc., if used.

If you created a swap volume earlier, add an appropriate entry to /etc/fstab.

root #  echo /dev/zvol/rpool/swap none swap defaults 0 0 >> /etc/fstab

Note that swap on ZFS is unstable. If you decide to use swap, please take following into account: always use long /dev/zvol aliases in configuration files. Never use a short /dev/zdX device name.

Next, update the portage tree:

root # ego sync
root # env-update
root # source /etc/profile

Installing ZFS userspace and bootloader

Installing the ZFS userspace tools and kernel modules

Install the ZFS packages and sync the portage tree, if required:

root # ego sync
root # emerge --ask sys-fs/zfs

Once it has successfully merged, add the following services to the boot runlevel of OpenRC:

root # rc-update add zfs-import boot
root # rc-update add zfs-mount boot

Add another two services to the default runlevel:

root # rc-update add zfs-share default
root # rc-update add zfs-zed default

Create a ZFS-friendly initramfs

The Funtoo stage3 includes a linux kernel and initramfs. The initramfs is designed to mount and start Funtoo Linux on a variety of file systems. The initramfs contained within the stage3 will not mount and start Funtoo in our ZFS storage pool. We must create an updated 'ZFS-friendly' initramfs.

Optional: Update to the latest sys-kernel/genkernel:

root # emerge --oneshot sys-kernel/genkernel

Use genkernel to create an initramfs capable of mounting our ZFS Storage Pool via the --zfs switch. Adjust --makeopts according to the number of available threads:

root # genkernel initramfs --no-clean --no-mountboot --makeopts=-j4 --kernel-config=/usr/src/linux/.config --zfs
root ##g##* Funtoo Linux Genkernel; Version 3.4.40.11-funtoo##!g##
root ##g##*##!g## Running with options: initramfs --no-clean --no-mountboot --makeopts=-j4 --kernel-config=/usr/src/linux/.config --zfs

root ##g##*##!g## Linux Kernel 4.5.2-1 for x86_64...
root ##g##*##!g## .. with config file /usr/src/linux-debian-sources-4.5.2/.config
root ##g##*##!g## busybox: >> Using cache
root ##g##*##!g## initramfs: >> Initializing...
root ##g##*##!g##         >> Appending base_layout cpio data...
root ##g##*##!g##         >> Appending auxilary cpio data...
root ##g##*##!g##         >> Copying keymaps
root ##g##*##!g##         >> Appending busybox cpio data...
root ##g##*##!g##         >> Appending modules cpio data...
root ##g##*##!g##         >> Appending zfs cpio data...
cp: cannot stat ‘/etc/zfs/zdev.conf’: No such file or directory
root ##y##*##!y## Could not copy file /etc/zfs/zdev.conf for ZFS
root ##g##*##!g##         >> Appending blkid cpio data...
root ##g##*##!g##         >> Appending modprobed cpio data...
root ##g##*##!g##         >> Compressing cpio data (.xz)...

root ##y##*##!y## WARNING... WARNING... WARNING...
root ##y##*##!y## Additional kernel cmdline arguments that *may* be required to boot properly...
root ##y##*##!y## add "dozfs" for ZFS volume management support
root ##y##*##!y## add either "real_root=ZFS" (bootfs autodetection) or "real_root=ZFS=<dataset>" to boot from a ZFS dataset

root ##g##*##!g## Do NOT report kernel bugs as genkernel bugs unless your bug
root ##g##*##!g## is about the default genkernel configuration...
root ##g##*##!g## 
root ##g##*##!g## Make sure you have the latest ~arch genkernel before reporting bugs.

Confirm the presence of the new initramfs:

root # ls /boot/*genkernel*
/boot/initramfs-genkernel-x86_64-4.5.2-1

Grub expects the initramfs filename to be of the form: initramfs-${KNAME}-${ARCH}-${KV}. This guide assumes the usage of debian-sources. Tailor it to your specific kernel name, platform, and kernel version. Forgetting to rename initramfs-genkernel to initramfs-debian-sources will render the system unbootable.

root # cd /boot
root # mv initramfs-genkernel-x86_64-4.5.2-1 initramfs-debian-sources-x86_64-4.5.2-1
root # ls /boot/*initramfs*
/boot/initramfs-debian-sources-x86_64-4.5.2-1

Installing GRUB 2

GRUB 2 must be built with support for ZFS Storage Pools on a single disk. This is achieved using the 'libzfs' USE flag.

root # echo "sys-boot/grub libzfs" >> /etc/portage/package.use
   Note

If you have defined GRUB_PLATFORMS in your /etc/portage/make.conf, please ensure that it includes 'pc': e.g. GRUB_PLATFORMS="efi-64 pc".

This is required for booting in BIOS (non-UEFI) mode, as described in this guide.

Now, install GRUB:

root # emerge grub

Configuring the Bootloader

When zpool created our storage pool (rpool), it created partitions under a GPT scheme. In order to boot Funtoo Linux on a GPT partion under legacy (BIOS) boot, sys-boot/grub requires a small partition, called a BIOS boot partition. By design, ZFS (zpool) left a very small unpartitioned space at the beginning of the disk. We will use sgdisk, which is part of sys-apps/gptfdisk, to format this free space into a BIOS boot partition.

root # sgdisk -a1 -n2:48:2047 -t2:EF02 -c2:"BIOS boot partition" /dev/disk/by-id/ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF

To avoid problems with GRUB, use partx to refresh the list of partitions that are 'seen' by the kernel. Do this for each drive (/dev/sda, /dev/sdb, etc.).

root # partx -u /dev/sda

A quick check to verify that GRUB 2 sees/supports ZFS:

root # touch /etc/mtab
root # grub-probe /
zfs

Installing GRUB2 to disk is as easy as:

root # grub-install /dev/disk/by-id/ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF
Installing for i386-pc platform.
Installation finished. No error reported.

Now, it's time for us to create grub's configuration file. First, we must edit a few GRUB 2 settings in /etc/default/grub:

   Important

The following is required to boot Funtoo Linux on ZFS!

Replace the line

   /etc/default/grub - before
#GRUB_CMDLINE_LINUX=""

with

   /etc/default/grub - after
GRUB_CMDLINE_LINUX="dozfs real_root=ZFS=rpool/ROOT/funtoo"

Now, create GRUB 2 configuration file:

root # grub-mkconfig -o /boot/grub/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/kernel-debian-sources-x86_64-4.5.2-1
Found initrd image: /boot/initramfs-genkernel-x86_64-4.5.2-1
done

If grub-mkconfig cannot find the initrd image, manually add initrd to the generated /boot/grub/grub.cfg, below the linux line:

   /boot/grub/grub.cfg - adding initrd below the linux line
echo    'Loading Linux x86_64-4.5.2-1 ...'
linux   /ROOT/funtoo@/boot/kernel-debian-sources-x86_64-4.5.2-1 root=ZFS=rpool/ROOT/funtoo ro dozfs real_root=ZFS
echo    'Loading initial ramdisk ...'
initrd  /ROOT/funtoo@/boot/initramfs-debian-sources-x86_64-4.5.2-1

A quick check to verify that the GRUB ZFS module is in place:

root # ls /boot/grub/*/zfs.mod
/boot/grub/i386-pc/zfs.mod

Final configuration

Configure your network according to the main installation guide.

Set the root password.

(chroot) # passwd

Exit the chroot and export your ZFS storage pool.

(chroot) # exit
root # umount -lR {dev,proc,sys}
root # cd /
root # zpool export rpool

Restart to boot into Funtoo Linux on a ZFS root!

After reboot

Snapshot

Take a snapshot of your Funtoo at installation.

root # zfs snapshot rpool/ROOT/funtoo@install

The use of snapshots, including sending snapshots as a method of backup, are not covered in this guide. See Further Reading.

ZFS Adjustable Replacement Cache (ARC) size

The Adjustable Replacement Cache (ARC) is a fundamental part of ZFS. Refer to this article by Aaron Toponce for details on how to set up an ARC.

Without configuration, ZFS will use up to 50% of your memory (RAM) for the ARC. It is possible to change this maximum. There are different ways to achieve this on both a temporary and persistent basis. One such way is to create and edit the file /etc/modprobe.d/zfs.conf, which affects the ZFS kernel module.

   /etc/modprobe.d/zfs.conf - set maximum ARC size to 4 GiB
options zfs zfs_arc_max=4294967296

where zfs_arc_max is set to a value in Bytes. After configuring this file, re-generate the initramfs. Rebooting will then apply this change.

To apply this change immediately without a reboot, issue the command:

root #  echo 4294967296 >> /sys/module/zfs/parameters/zfs_arc_max

Reference: https://wiki.gentoo.org/wiki/ZFS#ARC

After Kernel or ZFS updates

The default Funtoo Linux kernel (sys-kernel/debian-sources) does not automatically build a ZFS-capable initramfs. Similarly, the package sys-fs/zfs and its dependencies do not automatically build a ZFS-capable initramfs.

After each kernel update, you must recreate an initramfs. Similarly, sys-fs/zfs updates also require you to regenerate an initramfs. This is especially true for updates to sys-fs/zfs that introduce new storage pool features. Neglecting to update your initramfs will make your system unbootable.

First, rebuild sys-fs/zfs, sys-fs/zfs-kmod and sys-kernel/spl:

root # emerge --ask --verbose -1 zfs zfs-kmod spl

Then, follow the earlier instructions to create a new initramfs:

root # genkernel initramfs --no-clean --no-mountboot --makeopts=-j4 --kernel-config=/usr/src/linux/.config --zfs
root # cd /boot
root # mv initramfs-genkernel-x86_64-4.5.2-1 initramfs-debian-sources-x86_64-4.5.2-1

Finally, repeat the earlier instructions for generating /boot/grub/grub.cfg and manually adding the new initramfs as initrd to the generated /boot/grub/grub.cfg.

Further Reading

ZFS has many interesting features not covered by this guide.

Useful information and instructions can be found in the online reference manuals. See man zpool and man zfs.

Aaron Toponce's Zpool/ZFS Administration Guides - https://pthree.org/2012/12/04/zfs-administration-part-i-vdevs

ZFS on Linux - http://www.zfsonlinux.org

ZFS - Gentoo Wiki - https://wiki.gentoo.org/wiki/ZFS

Troubleshooting

Forgot to reset password?

You will need to chroot into your Funtoo on ZFS root installation if you forgot to set the root password. Repeat the earlier instructions to load the the live CD/USB, including the installation of ZFS kernel modules.

When the ZFS kernel modules are loaded, your existing ZFS Storage Pool (rpool) will be imported automatically. This will also result in an attempt to mount the various ZFS filesystems that you created. Mounting your root partition (/) will fail since this location is not empty; / is allocated to the live CD/USB distribution!

root # zpool status
  pool: rpool
 state: ONLINE
  scan: none requested
config:

	NAME                                             STATE     READ WRITE CKSUM
	rpool                                            ONLINE       0     0     0
	  ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF  ONLINE       0     0     0

errors: No known data errors

To get around this issue, first, manually export the pool.

root # zpool export rpool
root # zpool list
no pools available

Now, import your storage pool using the following command.

root # zpool import -o cachefile=/tmp/zpool.cache -R /mnt/funtoo -d /dev/disk/by-id/ rpool

This will import rpool and place your Funtoo install at /mnt/funtoo. Follow the earlier set of instructions to chroot into your Funtoo Installation on ZFS root.

Will not mount on first reboot?

Follow the above instructions on "Forgot to reset password?" to import and mount your storage pool (rpool) and chroot back into your Funtoo environment.

Things to check:

  • Was the bootfs property of rpool set? Use zpool get bootfs rpool to check
  • Was /tmp/zpool.cache copied into /mnt/funtoo/etc/zfs/ prior to chroot and creating the initramfs?
  • Was genkernel initramfs run with the --zfs switch and --kernel-config pointing to the correct configuration file?
  • Was GRUB installed and configured correctly?

rpool is 'busy' on zpool export

This happens when swapon is used. Swap must be turned off to free the pool for export.

Unable to add universe repository in Ubuntu?

See http://askubuntu.com/questions/761592/unable-to-apt-get-dist-upgrade-on-a-persistent-ubuntu-16-04-usb

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