Difference between pages "Kernel/configs/realtime" and "ZFS Install Guide"

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== Introduction ==
This page needs cleanup (blatantly stolen from http://proaudio.tuxfamily.org/wiki/index.php?title=DAW_Digital_Audio_Workstation which is CC:BY:SA). Bad spelling and grammar abound.}}
+
  
===Instructions for 3.x Kernels===
+
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.
  
With the current 3.x kernels series, we have one more possibility to get real-time operations to work: Control Groups, or cgroups in short. This method is not available with the rt-kernel.
+
=== Introduction to ZFS ===
  
For a general introduction, see [http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt cgroups kernel documentation].
+
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:
  
From it: "Control Groups provide a mechanism for aggregating/partitioning sets of tasks, and all their future children, into hierarchical groups with specialized behaviour."
+
* 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.
  
This is exactly what the real-time patch is doing: it provides a mechanism for aggregating the audio tasks, and for attributing them a higher priority than the other tasks. The same (and much more) can be done with the Control Groups, this with any recent kernel.
+
* 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.
  
On the long run, I think many of us will use a vanilla or gentoo kernel with an audio related cgroups set-up. But the rt kernel will remain in use, firstly because it has proven to be a good working solution, secondly because the developers of the rt patch will continue to experiment new solutions, and thirdly because cgroups adds a slight scheduling overhead, and some of us don't want it.
+
* 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.
  
For a jack related explanation, see [http://trac.jackaudio.org/wiki/Cgroups Some notes on CGroups].
+
* ZFS has the ZFS Intent Log and SLOG devices, which accelerates small synchronous write performance.
  
====RT scheduling cpu bandwidth and cgroups====
+
* 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.
In the kernel configuration, the minimal and sufficient cgroups set-up to get RT scheduling is:
+
  
General setup --->
+
* 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.
        [*] Control Group support --->
+
                  [*] Group CPU scheduler --->
+
                            [*] Group scheduling for SCHED_RR/FIFO
+
  
As you can see in its help, this last option will give us CONFIG_RT_GROUP_SCHED. With this, we get access to RT scheduling cpu bandwidth controlled via cgroups. The root cgroup has this setup correctly. Remember, RT operations is all about bandwidth allocation of resources, more bandwidth for some tasks imply less bandwidth and responsiveness for the others.
+
* ZFS send/receive implementation supports incremental update when doing backups. btrfs' send/receive implementation requires sending the entire snapshot.
  
====cgroups set-up====
+
* ZFS supports data deduplication, which is a memory hog and only works well for specialized workloads. btrfs has no equivalent.
  
We also need to install dev-libs/libcgroup, which provide tools and libraries to configure and manage kernel Control Groups.
+
* ZFS datasets have a hierarchical namespace while btrfs subvolumes have a flat namespace.
  
emerge libcgroup
+
* 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.
  
However when libcgroup is installed and the cgconfig service has been started, it creates a "sysdefault" cgroup and moves all tasks over there. The sysdefault group does not have RT bandwidth assigned to it. In this case jackd can not be started.
+
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).
  
There are several methods to configure cgroups for our purpose ([http://trac.jackaudio.org/wiki/Cgroups Some notes on CGroups]).
+
For a quick tour of ZFS and have a big picture of its common operations you can consult the page [[ZFS Fun]].
I started with the method 2, but it was necessary to add a namespace section. In consequence, the following set-up is a mix of method 2 and 3.
+
  
Edit /etc/cgroups/cgconfig.conf as follow:
+
=== Disclaimers ===
  
namespace {
+
{{fancywarning|This guide is a work in progress. Expect some quirks.}}
cpu = /;
+
{{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 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.  
group rtaudio {
+
perm {
+
task {
+
uid = root;
+
gid = audio;
+
}
+
admin {
+
uid = root;
+
gid = root;
+
}
+
}
+
cpu {
+
cpu.rt_runtime_us = 950000;
+
}
+
}
+
  
We create here a kernel cgroup named rtaudio. Root can manage it. The users in the audio group can use it. We use rtaudio to define the processor use of the RT processes. The members of the rtaudio cgroup (the RT threads of the programs which are member of rtaudio) can use the processor during 950000 us per second, the other tasks get the remaining time, 50000 us.
+
<pre>
 +
Name: sysresccd-4.2.0_zfs_0.6.2.iso  (545 MB)
 +
Release Date: 2014-02-25
 +
md5sum 01f4e6929247d54db77ab7be4d156d85
 +
</pre>
  
At that time, we need to explicitly add the programs that must get RT scheduling. For that, edit /etc/cgroups/cgrules.conf:
 
  
# One of the following line is needed for jack
+
'''[http://ftp.osuosl.org/pub/funtoo/distfiles/sysresccd/ Download System Rescue CD with ZFS]'''<br />
#@audio:jackd cpu rtaudio/
+
@audio:jackdbus  cpu rtaudio/
+
# Comment the 2 following lines if not using snd-aloop
+
@audio:alsa_in  cpu rtaudio/
+
@audio:alsa_out  cpu rtaudio/
+
# Add one line for each RT software
+
@audio:mplayer cpu rtaudio/
+
@audio:ardour    cpu rtaudio/
+
@audio:jamin    cpu rtaudio/
+
  
You must add one line per application you want to be in the rtaudio cgroup. In the future, jack will provide a mechanism to move the RT threads of its clients into the cgroup of jackd.
+
== 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:
  
We must configure PAM in /etc/security/limits.conf:
+
<console>
@audio  -  rtprio    99
+
Make a temporary directory
@audio  -  memlock    unlimited
+
# ##i##mkdir /tmp/loop
  
Starting cgroups with our configuration:
+
Mount the iso
# /etc/init.d/cgred start
+
# ##i##mount -o ro,loop /root/sysresccd-4.2.0_zfs_0.6.2.iso /tmp/loop
* Starting cgconfig service ...                                           [ ok ]
+
* Starting CGroup Rules Engine Daemon ...                                [ ok ]
+
  
Only the new processes will be managed by cgroups. It is best to start it at boot time:
+
Run the usb installer
rc-update add cgred default
+
# ##i##/tmp/loop/usb_inst.sh
 +
</console>
  
====Testing cgroups====
+
That should be all you need to do to get your flash drive working.
To test your set-up, you can use the 2 following small scripts, findrtp and findrtt.
+
  
findrtt will output the running programs which are member of rtaudio. findrtt will output all their threads.
+
== Booting the ISO ==
  
findrtp
+
{{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.'''}}
  
#!/bin/sh
+
== Creating partitions ==
for i in `cat /sys/fs/cgroup/cpu//rtaudio/cgroup.procs`;
+
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.
    do echo "Found pid $i which correspond at `cat /proc/$i/cmdline`";
+
done
+
  
and
+
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.
  
findrtt
+
==== gdisk (GPT Style) ====
  
#!/bin/sh
+
'''A Fresh Start''':
for i in `cat /sys/fs/cgroup/cpu//rtaudio/tasks`;
+
    do echo "Find pid $i which correspond to `cat /proc/$i/cmdline`";
+
done
+
  
Save them in your path and make them executable.
+
First lets make sure that the disk is completely wiped from any previous disk labels and partitions.
 +
We will also assume that <tt>/dev/sda</tt> is the target drive.<br />
  
Run them:
+
<console>
# findrtp
+
# ##i##sgdisk -Z /dev/sda
Trouvé le pid 1846 qui correspond à /usr/bin/jackdbusauto
+
</console>
Trouvé le pid 2123 qui correspond à /usr/bin/alsa_out-jploop-dploop-q1
+
Trouvé le pid 2124 qui correspond à /usr/bin/alsa_in-jcloop-dcloop-q1
+
Trouvé le pid 2162 qui correspond à timidity-iA-B2,8-Oj-EFreverb=0-s48000
+
Trouvé le pid 2259 qui correspond à mplayerdvb://2@
+
  
# findrtt
+
{{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.}}
Trouvé le pid 1846 qui correspond à /usr/bin/jackdbusauto
+
Trouvé le pid 2116 qui correspond à /usr/bin/jackdbusauto
+
Trouvé le pid 2117 qui correspond à /usr/bin/jackdbusauto
+
Trouvé le pid 2118 qui correspond à /usr/bin/jackdbusauto
+
Trouvé le pid 2119 qui correspond à /usr/bin/jackdbusauto
+
Trouvé le pid 2123 qui correspond à /usr/bin/alsa_out-jploop-dploop-q1
+
Trouvé le pid 2124 qui correspond à /usr/bin/alsa_in-jcloop-dcloop-q1
+
Trouvé le pid 2128 qui correspond à /usr/bin/alsa_out-jploop-dploop-q1
+
Trouvé le pid 2129 qui correspond à /usr/bin/alsa_out-jploop-dploop-q1
+
Trouvé le pid 2130 qui correspond à /usr/bin/alsa_out-jploop-dploop-q1
+
Trouvé le pid 2131 qui correspond à /usr/bin/alsa_in-jcloop-dcloop-q1
+
Trouvé le pid 2162 qui correspond à timidity-iA-B2,8-Oj-EFreverb=0-s48000
+
Trouvé le pid 2170 qui correspond à timidity-iA-B2,8-Oj-EFreverb=0-s48000
+
Trouvé le pid 2171 qui correspond à timidity-iA-B2,8-Oj-EFreverb=0-s48000
+
Trouvé le pid 2172 qui correspond à timidity-iA-B2,8-Oj-EFreverb=0-s48000
+
Trouvé le pid 2259 qui correspond à mplayerdvb://2@
+
Trouvé le pid 2339 qui correspond à mplayerdvb://2@
+
Trouvé le pid 2340 qui correspond à mplayerdvb://2@
+
Trouvé le pid 2341 qui correspond à mplayerdvb://2@
+
  
To see which threads are RT, we can use ps:
+
Now that we have a clean drive, we will create the new layout.
ps -eLo rtprio,pri,cgroup,class,pid,pcpu,%mem,user,comm --sort pri|less
+
RTPRIO PRI CGROUP                      CLS  PID %CPU %MEM USER COMMAND
+
...
+
    -  19 2:cpu:/rtaudio              TS  2613  0.0  1.0 dom      jackdbus
+
    -  19 2:cpu:/rtaudio              TS  2613  0.0  1.0 dom      jackdbus
+
    -  19 2:cpu:/rtaudio              TS  2613  0.0  1.0 dom      jackdbus
+
    10  50 2:cpu:/rtaudio              FF  2613  0.4  1.0 dom      jackdbus
+
    -  19 2:cpu:/rtaudio              TS  2613  0.0  1.0 dom      jackdbus
+
...
+
    -  19 2:cpu:/rtaudio              TS  3642  0.0  1.0 dom      alsa_out
+
    -  19 2:cpu:/rtaudio              TS  3642  0.0  1.0 dom      alsa_out
+
    -  19 2:cpu:/rtaudio              TS  3642  0.0  1.0 dom      alsa_out
+
    5  45 2:cpu:/rtaudio              FF  3642  0.5  1.0 dom      alsa_out
+
    -  19 2:cpu:/rtaudio              TS  3643  0.0  1.0 dom      alsa_in
+
    -  19 2:cpu:/rtaudio              TS  3643  0.0  1.0 dom      alsa_in
+
    -  19 2:cpu:/rtaudio              TS  3643  0.0  1.0 dom      alsa_in
+
    5  45 2:cpu:/rtaudio              FF  3643  0.5  1.0 dom      alsa_in
+
    -  19 2:cpu:/rtaudio              TS  3664  0.0  1.3 dom      timidity
+
    -  19 2:cpu:/rtaudio              TS  3664  0.0  1.3 dom      timidity
+
    -  19 2:cpu:/rtaudio              TS  3664  0.0  1.3 dom      timidity
+
    5  45 2:cpu:/rtaudio              FF  3664  0.0  1.3 dom      timidity
+
    -  19 2:cpu:/rtaudio              TS  30170  6.1  1.4 dom      mplayer
+
    -  19 2:cpu:/rtaudio              TS  30170  0.0  1.4 dom      mplayer
+
    -  19 2:cpu:/rtaudio              TS  30170  0.0  1.4 dom      mplayer
+
    5  45 2:cpu:/rtaudio              FF  30170  0.1  1.4 dom      mplayer
+
  
The FF threads are the real-time ones. We will see the same result with htop, but with other priority numbers (I prefer htop).
+
First open up the application:
  
Another test is to lower jack latency. Run qjackctl and play with the parameters. With the Control Groups, I can lower jack latency with the gentoo-sources from 42,7 msec (1024 Frames/Period, 48kHz, 2 Periods/Buffer) to 0,667 msec (16 Frames/Period) without more xruns (only at applications start-up), which is as good as with the rt-sources.
+
<console>
 +
# ##i##gdisk /dev/sda
 +
</console>
 +
 
 +
'''Create Partition 1''' (boot):
 +
<console>
 +
Command: ##i##n ↵
 +
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>
 +
 
 +
'''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>
 +
# ##i##mkfs.ext2 -m 1 /dev/sda1
 +
</console>
 +
 
 +
=== Create the zpool ===
 +
We will first create the pool. The pool will be named `tank` and the disk will be aligned to 4096 (using ashift=12)
 +
<console># ##i##zpool create -f -o ashift=12 -o cachefile= -O compression=on -m none -R /mnt/funtoo tank /dev/sda3</console>
 +
 
 +
=== Create the zfs datasets ===
 +
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: <tt>/home</tt>, <tt>/var</tt>, <tt>/usr/src</tt>, and <tt>/usr/portage</tt>.
 +
 
 +
<console>
 +
Create some empty containers for organization purposes, and make the dataset that will hold /
 +
# ##i##zfs create -p tank/funtoo
 +
# ##i##zfs create -o mountpoint=/ tank/funtoo/root
 +
 
 +
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>
 +
 
 +
=== Create your swap zvol ===
 +
For modern machines that have greater than 4 GB of RAM, A swap size of 2G should be enough. However if your machine doesn't have a lot of RAM, the rule of thumb is either 2x the RAM or RAM + 1 GB.
 +
 
 +
For this tutorial we will assume that it is a newer machine and make a 2 GB swap.
 +
 
 +
<console>
 +
# ##i##zfs create -o sync=always -o primarycache=metadata -o secondarycache=none -o volblocksize=4K -V 2G tank/swap
 +
</console>
 +
{{fancywarning|ZFS swap is not stable and should be used with precautions.}}
 +
 
 +
=== Format your swap zvol ===
 +
<console>
 +
# ##i##mkswap -f /dev/zvol/tank/swap
 +
# ##i##swapon /dev/zvol/tank/swap
 +
</console>
 +
 
 +
Now we will continue to install funtoo.
 +
 
 +
== Installing Funtoo ==
 +
 
 +
=== Pre-Chroot ===
 +
 
 +
<console>
 +
Go into the directory that you will chroot into
 +
# ##i##cd /mnt/funtoo
 +
 
 +
Make a boot folder and mount your boot drive
 +
# ##i##mkdir boot
 +
# ##i##mount /dev/sda1 boot
 +
</console>
 +
 
 +
[[Funtoo_Linux_Installation|Now download and extract the Funtoo stage3 ...]]
 +
 
 +
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 --rbind /dev dev
 +
# ##i##mount --rbind /sys sys
 +
 
 +
Copy network settings
 +
# ##i##cp -f /etc/resolv.conf etc
 +
 
 +
Make the zfs folder in 'etc' and copy your zpool.cache
 +
# ##i##mkdir etc/zfs
 +
# ##i##cp /etc/zfs/zpool.cache etc/zfs
 +
 
 +
Chroot into Funtoo
 +
# ##i##env -i HOME=/root TERM=$TERM chroot . bash -l
 +
</console>
 +
 
 +
=== In Chroot ===
 +
 
 +
<console>
 +
Create a symbolic link to your mountpoints
 +
# ##i##ln -sf /proc/mounts /etc/mtab
 +
 
 +
Sync your tree
 +
# ##i##emerge --sync
 +
</console>
 +
 
 +
=== Add filesystems to /etc/fstab ===
 +
 
 +
Before we continue to compile and or install our kernel in the next step, we will edit the <tt>/etc/fstab</tt> file because if we decide to install our kernel through portage, portage will need to know where our <tt>/boot</tt> is, so that it can place the files in there.
 +
 
 +
Edit <tt>/etc/fstab</tt>:
 +
 
 +
<pre>
 +
# <fs>                  <mountpoint>    <type>          <opts>          <dump/pass>
 +
 
 +
/dev/sda1              /boot          ext2            defaults        0 2
 +
/dev/zvol/tank/swap    none            swap            sw              0 0
 +
</pre>
 +
 
 +
== Kernel Configuration ==
 +
...wip
 +
 
 +
== Installing the ZFS userspace tools and kernel modules ==
 +
Emerge {{Package|sys-fs/zfs}}. This package will bring in {{Package|sys-kernel/spl}}, and {{Package|sys-fs/zfs-kmod}} as its dependencies:
 +
 
 +
<console>
 +
# ##i##emerge zfs
 +
</console>
 +
 
 +
Check to make sure that the zfs tools are working. The <code>zpool.cache</code> file that you copied before should be displayed.
 +
 
 +
<console>
 +
# ##i##zpool status
 +
# ##i##zfs list
 +
</console>
 +
 
 +
If everything worked, continue.
 +
 
 +
== Create the initramfs ==
 +
There are two ways to do this, you can use "genkernel" or "bliss-initramfs". Both will be shown.
 +
 
 +
=== genkernel ===
 +
Install genkernel and run it:
 +
<console>
 +
# ##i##emerge genkernel
 +
 
 +
You only need to add --luks if you used encryption
 +
# ##i##genkernel --zfs --luks initramfs
 +
</console>
 +
 
 +
== Installing & Configuring the Bootloader ==
 +
 
 +
=== GRUB 2 ===
 +
<console>
 +
# ##i##emerge grub
 +
</console>
 +
 
 +
You can check that grub is version 2.00 by typing the following command:
 +
 
 +
<console>
 +
# ##i##grub-install --version
 +
grub-install (GRUB) 2.00
 +
</console>
 +
 
 +
Now install grub to the drive itself (not a partition):
 +
<console>
 +
# ##i##grub-install /dev/sda
 +
</console>
 +
 
 +
You should receive the following message:
 +
 
 +
<console>
 +
Installation finished. No error reported.
 +
</console>
 +
 
 +
You should now see some a grub directory with some files inside your /boot folder:
 +
 
 +
<console>
 +
# ##i##ls -l /boot/grub
 +
total 2520
 +
-rw-r--r-- 1 root root    1024 Jan  4 16:09 grubenv
 +
drwxr-xr-x 2 root root    8192 Jan 12 14:29 i386-pc
 +
drwxr-xr-x 2 root root    4096 Jan 12 14:28 locale
 +
-rw-r--r-- 1 root root 2555597 Feb  4 11:50 unifont.pf2
 +
</console>
 +
 
 +
=== boot-update ===
 +
boot-update comes as a dependency of grub2, so if you already installed grub, it's already on your system!
 +
 
 +
==== Genkernel ====
 +
If your using genkernel you must add 'real_root=ZFS=<root>' and 'dozfs' to your params.
 +
Example entry for <tt>/etc/boot.conf</tt>:
 +
 
 +
<pre>
 +
"Funtoo ZFS" {
 +
        kernel vmlinuz[-v]
 +
        initrd initramfs-genkernel-x86_64[-v]
 +
        params real_root=ZFS=tank/funtoo/root
 +
        params += dozfs=force
 +
        # Also add 'params += crypt_root=/dev/sda3' if you used encryption
 +
        # Adjust the above setting to your system if needed
 +
 
 +
        # You should also add 'root=none' to your params (not 'params +=') if you plan to use it along with boot-update
 +
        # If root variable will not be set, boot-update will fail to generate boot.conf
 +
        # This is right for <=sys-boot/boot-update-1.6.11 on 16.08.2014 date
 +
}
 +
</pre>
 +
 
 +
After editing /etc/boot.conf, you just need to run boot-update to update grub.cfg
 +
 
 +
<console>
 +
###i## boot-update
 +
</console>
 +
 
 +
=== LILO (Optional if you are using another bootloader) ===
 +
Now that bliss-boot generated the lilo.conf file, move that config file to its appropriate location
 +
and install lilo to the MBR:
 +
 
 +
<console>
 +
# ##i##mv lilo.conf /etc
 +
# ##i##lilo
 +
 
 +
You should see the following:
 +
 
 +
Warning: LBA32 addressing assumed
 +
Added Funtoo + *
 +
One warning was issued
 +
</console>
 +
 
 +
== Final configuration ==
 +
=== Add the zfs tools to openrc ===
 +
<console># ##i##rc-update add zfs boot</console>
 +
 
 +
=== Clean up and reboot ===
 +
We are almost done, we are just going to clean up, '''set our root password''', and unmount whatever we mounted and get out.
 +
 
 +
<console>
 +
Delete the stage3 tarball that you downloaded earlier so it doesn't take up space.
 +
# ##i##cd /
 +
# ##i##rm stage3-latest.tar.xz
 +
 
 +
Set your root password
 +
# ##i##passwd
 +
>> Enter your password, you won't see what you are writing (for security reasons), but it is there!
 +
 
 +
Get out of the chroot environment
 +
# ##i##exit
 +
 
 +
Unmount all the kernel filesystem stuff and boot (if you have a separate /boot)
 +
# ##i##umount -l proc dev sys boot
 +
 
 +
Turn off the swap
 +
# ##i##swapoff /dev/zvol/tank/swap
 +
 
 +
Export the zpool
 +
# ##i##cd /
 +
# ##i##zpool export tank
 +
 
 +
Reboot
 +
# ##i##reboot
 +
</console>
 +
 
 +
{{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.'''}}
 +
 
 +
and that should be enough to get your system to boot on ZFS.
 +
 
 +
== After reboot ==
 +
 
 +
=== Forgot to reset password? ===
 +
==== 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:
 +
<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>
 +
 
 +
==== Using bliss-initramfs ====
 +
If you forgot to reset your password and are using '''bliss-initramfs''', you can add the '''su''' option to your bootloader parameters and the initramfs will throw you into the rootfs of your drive. In there you can run 'passwd' and then type 'exit'. Once you type 'exit', the initramfs will continue to boot your system as normal.
 +
 
 +
=== Create initial ZFS Snapshot ===
 +
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.
 +
 
 +
To take the snapshot of your system, type the following:
 +
<console># ##i##zfs snapshot -r tank@install</console>
 +
 
 +
To see if your snapshot was taken, type:
 +
<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):
 +
<console># ##i##zfs rollback tank/funtoo/root@install</console>
 +
 
 +
{{fancyimportant|'''For a detailed overview, presentation of ZFS' capabilities, as well as usage examples, please refer to the [[ZFS_Fun|ZFS Fun]] page.'''}}
 +
 
 +
== Troubleshooting ==
 +
 
 +
=== Starting from scratch ===
 +
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>
 +
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
 +
position and size will not give us access to the old files in this partition.
 +
# ##i##mkfs.ext2 /dev/sda1
 +
# ##i##sgdisk -Z /dev/sda
 +
</console>
 +
 
 +
Now start the guide again :).
 +
 
 +
[[Category:HOWTO]]
 +
[[Category:Filesystems]]
 +
[[Category:Featured]]
 +
[[Category:Install]]
 +
 
 +
__NOTITLE__

Revision as of 14:59, January 5, 2015

Introduction

This tutorial will show you how to install Funtoo on ZFS (rootfs). This tutorial is meant to be an "overlay" over the Regular Funtoo Installation. Follow the normal installation and only use this guide for steps 2, 3, and 8.

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

Warning

This guide is a work in progress. Expect some quirks.

Important

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 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.

Name: sysresccd-4.2.0_zfs_0.6.2.iso  (545 MB)
Release Date: 2014-02-25
md5sum 01f4e6929247d54db77ab7be4d156d85


Download System Rescue CD with ZFS

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:

Make a temporary directory
# mkdir /tmp/loop

Mount the iso
# mount -o ro,loop /root/sysresccd-4.2.0_zfs_0.6.2.iso /tmp/loop

Run the usb installer
# /tmp/loop/usb_inst.sh

That should be all you need to do to get your flash drive working.

Booting the ISO

Warning

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.

Creating partitions

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.

gdisk (GPT Style)

A Fresh Start:

First lets make sure that the disk is completely wiped from any previous disk labels and partitions. We will also assume that /dev/sda is the target drive.

# sgdisk -Z /dev/sda
Warning

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.

Now that we have a clean drive, we will create the new layout.

First open up the application:

# gdisk /dev/sda

Create Partition 1 (boot):

Command: n ↵
Partition Number: 
First sector: 
Last sector: +250M ↵
Hex Code: 

Create Partition 2 (BIOS Boot Partition):

Command: n ↵
Partition Number: 
First sector: 
Last sector: +32M ↵
Hex Code: EF02 ↵

Create Partition 3 (ZFS):

Command: n ↵
Partition Number: 
First sector: 
Last sector: 
Hex Code: bf00 ↵

Command: 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: w ↵


Format your /boot partition

# mkfs.ext2 -m 1 /dev/sda1

Create the zpool

We will first create the pool. The pool will be named `tank` and the disk will be aligned to 4096 (using ashift=12)

# zpool create -f -o ashift=12 -o cachefile= -O compression=on -m none -R /mnt/funtoo tank /dev/sda3

Create the zfs datasets

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: /home, /var, /usr/src, and /usr/portage.

Create some empty containers for organization purposes, and make the dataset that will hold /
# zfs create -p tank/funtoo
# zfs create -o mountpoint=/ tank/funtoo/root

Optional, but recommended datasets: /home
# zfs create -o mountpoint=/home tank/funtoo/home

Optional datasets: /usr/src, /usr/portage/{distfiles,packages}
# zfs create -o mountpoint=/usr/src tank/funtoo/src
# zfs create -o mountpoint=/usr/portage -o compression=off tank/funtoo/portage
# zfs create -o mountpoint=/usr/portage/distfiles tank/funtoo/portage/distfiles
# zfs create -o mountpoint=/usr/portage/packages tank/funtoo/portage/packages

Create your swap zvol

For modern machines that have greater than 4 GB of RAM, A swap size of 2G should be enough. However if your machine doesn't have a lot of RAM, the rule of thumb is either 2x the RAM or RAM + 1 GB.

For this tutorial we will assume that it is a newer machine and make a 2 GB swap.

# zfs create -o sync=always -o primarycache=metadata -o secondarycache=none -o volblocksize=4K -V 2G tank/swap
Warning

ZFS swap is not stable and should be used with precautions.

Format your swap zvol

# mkswap -f /dev/zvol/tank/swap
# swapon /dev/zvol/tank/swap

Now we will continue to install funtoo.

Installing Funtoo

Pre-Chroot

Go into the directory that you will chroot into
# cd /mnt/funtoo

Make a boot folder and mount your boot drive
# mkdir boot
# mount /dev/sda1 boot

Now download and extract the Funtoo stage3 ...

Once you've extracted the stage3, do a few more preparations and chroot into your new funtoo environment:

Bind the kernel related directories
# mount -t proc none proc
# mount --rbind /dev dev
# mount --rbind /sys sys

Copy network settings
# cp -f /etc/resolv.conf etc

Make the zfs folder in 'etc' and copy your zpool.cache
# mkdir etc/zfs
# cp /etc/zfs/zpool.cache etc/zfs

Chroot into Funtoo
# env -i HOME=/root TERM=$TERM chroot . bash -l

In Chroot

Create a symbolic link to your mountpoints
# ln -sf /proc/mounts /etc/mtab

Sync your tree
# emerge --sync

Add filesystems to /etc/fstab

Before we continue to compile and or install our kernel in the next step, we will edit the /etc/fstab file because if we decide to install our kernel through portage, portage will need to know where our /boot is, so that it can place the files in there.

Edit /etc/fstab:

# <fs>                  <mountpoint>    <type>          <opts>          <dump/pass>

/dev/sda1               /boot           ext2            defaults        0 2
/dev/zvol/tank/swap     none            swap            sw              0 0

Kernel Configuration

...wip

Installing the ZFS userspace tools and kernel modules

Emerge No results. This package will bring in No results, and No results as its dependencies:

# emerge zfs

Check to make sure that the zfs tools are working. The zpool.cache file that you copied before should be displayed.

# zpool status
# zfs list

If everything worked, continue.

Create the initramfs

There are two ways to do this, you can use "genkernel" or "bliss-initramfs". Both will be shown.

genkernel

Install genkernel and run it:

# emerge genkernel

You only need to add --luks if you used encryption
# genkernel --zfs --luks initramfs

Installing & Configuring the Bootloader

GRUB 2

# emerge grub

You can check that grub is version 2.00 by typing the following command:

# grub-install --version
grub-install (GRUB) 2.00

Now install grub to the drive itself (not a partition):

# grub-install /dev/sda

You should receive the following message:

Installation finished. No error reported.

You should now see some a grub directory with some files inside your /boot folder:

# ls -l /boot/grub
total 2520
-rw-r--r-- 1 root root    1024 Jan  4 16:09 grubenv
drwxr-xr-x 2 root root    8192 Jan 12 14:29 i386-pc
drwxr-xr-x 2 root root    4096 Jan 12 14:28 locale
-rw-r--r-- 1 root root 2555597 Feb  4 11:50 unifont.pf2

boot-update

boot-update comes as a dependency of grub2, so if you already installed grub, it's already on your system!

Genkernel

If your using genkernel you must add 'real_root=ZFS=<root>' and 'dozfs' to your params. Example entry for /etc/boot.conf:

"Funtoo ZFS" {
        kernel vmlinuz[-v]
        initrd initramfs-genkernel-x86_64[-v]
        params real_root=ZFS=tank/funtoo/root
        params += dozfs=force
        # Also add 'params += crypt_root=/dev/sda3' if you used encryption
        # Adjust the above setting to your system if needed

        # You should also add 'root=none' to your params (not 'params +=') if you plan to use it along with boot-update
        # If root variable will not be set, boot-update will fail to generate boot.conf
        # This is right for <=sys-boot/boot-update-1.6.11 on 16.08.2014 date
}

After editing /etc/boot.conf, you just need to run boot-update to update grub.cfg

# boot-update

LILO (Optional if you are using another bootloader)

Now that bliss-boot generated the lilo.conf file, move that config file to its appropriate location and install lilo to the MBR:

# mv lilo.conf /etc
# lilo

You should see the following:

Warning: LBA32 addressing assumed
Added Funtoo + *
One warning was issued

Final configuration

Add the zfs tools to openrc

# rc-update add zfs boot

Clean up and reboot

We are almost done, we are just going to clean up, set our root password, and unmount whatever we mounted and get out.

Delete the stage3 tarball that you downloaded earlier so it doesn't take up space.
# cd /
# rm stage3-latest.tar.xz

Set your root password
# passwd
>> Enter your password, you won't see what you are writing (for security reasons), but it is there!

Get out of the chroot environment
# exit

Unmount all the kernel filesystem stuff and boot (if you have a separate /boot)
# umount -l proc dev sys boot

Turn off the swap
# swapoff /dev/zvol/tank/swap

Export the zpool
# cd /
# zpool export tank

Reboot
# reboot
Important

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.

and that should be enough to get your system to boot on ZFS.

After reboot

Forgot to reset password?

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:

# zpool import -f -R /mnt/funtoo tank
# chroot /mnt/funtoo bash -l
# passwd
# exit
# zpool export -f tank
# reboot

Using bliss-initramfs

If you forgot to reset your password and are using bliss-initramfs, you can add the su option to your bootloader parameters and the initramfs will throw you into the rootfs of your drive. In there you can run 'passwd' and then type 'exit'. Once you type 'exit', the initramfs will continue to boot your system as normal.

Create initial ZFS Snapshot

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.

To take the snapshot of your system, type the following:

# zfs snapshot -r tank@install

To see if your snapshot was taken, type:

# zfs list -t snapshot

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):

# zfs rollback tank/funtoo/root@install
Important

For a detailed overview, presentation of ZFS' capabilities, as well as usage examples, please refer to the ZFS Fun page.

Troubleshooting

Starting from scratch

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:

Destroy the pool and any snapshots and datasets it has
# 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
position and size will not give us access to the old files in this partition.
# mkfs.ext2 /dev/sda1
# sgdisk -Z /dev/sda

Now start the guide again :).