LVM Install Guide

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Introduction

Note

This tutorial will show you how to install Funtoo, including the rootfs, on logical volumes. This guide is meant to complement the regular Funtoo Installation Guide. It is recommended that you open it in another tab/window and follow along with it as we will only be documenting the steps that are different or in addition to the regular guide.

LVM (Logical Volume Management) offers a much more flexible way of managing your storage devices. Not only does it allow you to resize your volumes

Live CD

Please read the Live CD section in the regular guide. The only thing you need in addition to the requirements it mentions is the sys-fs/lvm2 package or equivalent. If you use System Rescue CD, it includes the lvm2 package.

Prepare the drives and partitions

Note

For this guide, we are assuming you are using MBR, that you have a /dev/sda1 (a boot drive) and /dev/sdb1 (a system drive), and that you are only using LVM with one drive, even though LVM supports adding multiple hard disks and partitions to a volume group. Please adapt these instructions to suit your needs.

Preparing the hard disk for an LVM install isn't much different from a normal install except that we won't be creating a bunch of partitions as we are going to use logical volumes instead.

Find the disk:

# fdisk -l

Verify the disk:

# fdisk -l /dev/sdb

Zap the disk:

# sgdisk --zap-all /dev/sdb

Create the partition table:

Note

If you are using MBR, review paritioning Partitioning Using fdisk and if you are using GPT, review Partitioning using gdisk. The basic idea is to create what ncessary and then allocate the rest for LVM.

For MBR, this is the boot partition (if you want it on the system drive), every else goes to LVM like so:

# fdisk /dev/sdb
Disk /dev/sdb: 596.2 GiB, 640135028736 bytes, 1250263728 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xaa6abfe1

Device    Boot     Start        End    Blocks  Id System
/dev/sdb1           2048     264191    131072  83 Linux
/dev/sdb2         264192 1250263727 624999768  83 Linux

For GPT, this is the BIOS boot partion and the boot partition (if you want them on the system drive), every else goes to LVM like so:

# gdisk /dev/sdb
Disk /dev/sdb: 596.2 GiB, 640135028736 bytes, 1250263728 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x6ba8799c

Device    Boot     Start        End    Blocks  Id System
/dev/sdb1           2048       6143      2048  ef EFI (FAT-12/16/32)
/dev/sdb2           6144     268287    131072  83 Linux
/dev/sdb3         268288 1250263727 624997720  83 Linux

You'll notice in both cases that a swap partition wasn't created. This is becasue if one is desired, it can be done in LVM.

Create the physical volume:

Note

As a reminder, for this guide, we are assuming you are using MBR, that you have a /dev/sda1 (a boot drive) and /dev/sdb1 (a system drive), and that you are only using LVM with one drive. Change this to suit your purposes.

Our first step is to create a physical volume which basically just tells the lvm where to write the data to.

# pvcreate -f -f /dev/sdb1
  Physical volume "/dev/sdb1" successfully created

Display the physical volume:

# pvdisplay
  "/dev/sdb1" is a new physical volume of "596.17 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb1
  VG Name               
  PV Size               596.17 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               IDDrWr-t3PD-7t31-fRQ3-pay2-eMGy-1NgrD0

Create the volume group:

Now that we have a place to store our data we need to create a volume group for it. A volume group is simply a named group of at least one physical volume. This allows multiple physical volumes to be used to store data. In our simple example we only have one physical volume so we'll create a volume group and add our physical volume to it in one command. We are going to call our volume group "funtoo" but you can name it anything you want.

# vgcreate funtoo /dev/sdb1
  Volume group "funtoo" successfully created

Display the volume group:

# vgdisplay
  --- Volume group ---
  VG Name               funtoo
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               596.17 GiB
  PE Size               4.00 MiB
  Total PE              152619
  Alloc PE / Size       0 / 0   
  Free  PE / Size       152619 / 596.17 GiB
  VG UUID               jFubWA-SGaa-w3C7-Zrst-9Hqo-mWPZ-9JqYZ4

Create the logical volumes:

We now come to the heart of using LVM, logical volumes. Here we get to create logical volumes to store our data. Remember that the best part of LVM is the ability to resize volumes later on the fly so keep that in mind when deciding how big to make volumes. No need to allocate all your space right away. Also keep in mind when choosing a file system type that it must support resizing in order to take advantage of LVM's resizing features.

For our simple example we are only going to create 4 logical volumes and use them for: (SWAP) /(ROOT), /home/my and /home/my/media.

# lvcreate -L 32G -n SWAP funtoo
  Logical volume "SWAP" created
# lvcreate -L 64G -n ROOT funtoo
  Logical volume "ROOT" created
# lvcreate -L 128G -n home_my funtoo
  Logical volume "home_my" created
# lvcreate -L 256G -n home_my_media funtoo
  Logical volume "home_my_media" created

Display the logical volumes:

# lvdisplay
  --- Logical volume ---
  LV Path                /dev/funtoo/SWAP
  LV Name                SWAP
  VG Name                funtoo
  LV UUID                VkdEAk-Jshp-qcQ0-jU7m-m7f4-fyG6-1FZJlh
  LV Write Access        read/write
  LV Creation host, time funtoo, 2014-07-24 04:39:19 -0400
  LV Status              available
  # open                 0
  LV Size                32.00 GiB
  Current LE             8192
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:1
   
  --- Logical volume ---
  LV Path                /dev/funtoo/ROOT
  LV Name                ROOT
  VG Name                funtoo
  LV UUID                2WE7dL-R5BN-dM78-eMx5-hwS8-SjWJ-mUjzL4
  LV Write Access        read/write
  LV Creation host, time funtoo, 2014-07-24 04:39:24 -0400
  LV Status              available
  # open                 0
  LV Size                64.00 GiB
  Current LE             16384
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:2
   
  --- Logical volume ---
  LV Path                /dev/funtoo/home_my
  LV Name                home_my
  VG Name                funtoo
  LV UUID                OJnpYM-399Y-8pa3-iMTY-Nle3-IyK1-keDtng
  LV Write Access        read/write
  LV Creation host, time funtoo, 2014-07-24 04:40:16 -0400
  LV Status              available
  # open                 0
  LV Size                128.00 GiB
  Current LE             32768
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:3
   
  --- Logical volume ---
  LV Path                /dev/funtoo/home_my_media
  LV Name                home_my_media
  VG Name                funtoo
  LV UUID                tt7cin-igC4-VD85-fDKV-J692-fV3F-auJYcU
  LV Write Access        read/write
  LV Creation host, time funtoo, 2014-07-24 04:40:30 -0400
  LV Status              available
  # open                 0
  LV Size                256.00 GiB
  Current LE             65536
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:4

Activate swap:

# mkswap /dev/mapper/funtoo-SWAP
Setting up swapspace version 1, size = 33554428 KiB
no label, UUID=ccc83857-28da-4508-a393-84e974e0eeb1
# swapon /dev/mapper/funtoo-SWAP

Create the filesystems:

Note

Before proceeding you should read through the brief section Creating filesystems in the install guide and decide what type of filesystem you would like to use. Do not actually create any file systems though, we will cover that below.

# mkfs.ext2       /dev/sda1
[...]
# mkfs.ext4       /dev/mapper/funtoo-ROOT
mke2fs 1.42.10 (18-May-2014)
Creating filesystem with 16777216 4k blocks and 4194304 inodes
Filesystem UUID: 0ab8f9ab-e824-4d69-a9c4-201d4ccd99ac
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
	4096000, 7962624, 11239424

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done   
# mkfs.ext4       /dev/mapper/funtoo-home_my
mke2fs 1.42.10 (18-May-2014)
Creating filesystem with 33554432 4k blocks and 8388608 inodes
Filesystem UUID: 46e394c1-3635-4f13-ba51-10c537d2b5ed
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
	4096000, 7962624, 11239424, 20480000, 23887872

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done     
# mkfs.xfs        /dev/mapper/funtoo-home_my_media
meta-data=/dev/mapper/funtoo-home_my_media isize=256    agcount=4, agsize=16777216 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=67108864, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=32768, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

Label the filesystems:

# e2label /dev/sda1 boot

Prepare for chroot

Activiate the volumes:

# vgscan
# vgchange -a y

Mount the filesystems:

# mkdir -p /mnt/funtoo
# mount /dev/mapper/funtoo-ROOT /mnt/funtoo
# mkdir -p /mnt/funtoo/boot
# mount /dev/sda1 /mnt/funtoo/boot
# mkdir -p /mnt/funtoo/home/my
# mount /dev/mapper/funtoo-home_my /mnt/funtoo/home/my
# mkdir -p /mnt/funtoo/home/my/media
# mount /dev/mapper/funtoo-home_my_media /mnt/funtoo/home/my/media

Resume from Funtoo Linux Installation

You may safely resume from Installing the Stage 3 tarball with few exceptions:

fstab

# <filesystem>                  <mountpoint>        <type>      <opts>      <dump>      <pass>
/dev/funtoo/SWAP                none                swap        sw          0           0
/dev/funtoo/ROOT                /                   ext4        noatime     0           1
LABEL=boot                      /boot               ext2        noatime     0           0
/dev/funtoo/home_my             /home/my            ext4        noatime     0           2
/dev/funtoo/home_my_media       /home/my/media      xfs         noatime     0           2

kernel

Enable kernel options:

General setup --->
      [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support
Device Drivers --->
      Generic Driver Options ---> 
      [*] Maintain a devtmpfs filesystem to mount at /dev
Device Drivers --->
      [*] Multiple devices driver support --->
      <*>Device Mapper Support

Build initramfs (genkernel):

Note

This builds only an initramfs with lvm support. It does not build the whole kernel so you still have to do that.

# genkernel --lvm initramfs

boot-update

boot {
  generate grub
  default "Funtoo Linux"
  timeout 3
}

"Funtoo Linux" {
  kernel kernel-genkernel-x86_64-3.14.13
  initrd initramfs-genkernel-x86_64-3.14.13
  params += dolvm real_root=/dev/mapper/funtoo-ROOT rootfstype=ext4 resume=swap:/dev/mapper/funtoo-SWAP quiet
}

software

# emerge -va lvm2

For the most part, LVM "just works" without any additional configuration. This is especially true for versions below 2.02.107. If you are using >=sys-fs/lvm2-2.02.107 with Funtoo, there are two features be desired that are turned off by default:

The Metadata Daemon (lvmetad)

Thinly-Provisioned Logical Volumes (Thin Volumes)

Enabling either is simply a matter of enabling their USE flags.

Cleaning up

# exit
# cd /
# cat /proc/mounts | grep funtoo | awk '{print $2}' | grep "^$MOUNTPOINT" | sort -r | xargs umount
# umount /mnt/funtoo
# swapoff -v /dev/mapper/funtoo-SWAP
# vgchange -a n
# init 0

Special notes

Resizing

Note

Resizing is filesystem specific. Most can be grown but cannot be shrunk.

Growing /home/my by 8G

# lvextend -L+8G /dev/mapper/funtoo-home_my
ext2/ext3/ext4
# resize2fs /mnt/funtoo/home/my
xfs
# xfs_growfs /mnt/funtoo/home/my

Shrinking /home/my by 8G

Note

You generally need to umount first.

ext2/ext3/ext4
# umount /mnt/funtoo/home/my
# lvreduce -r -L -8G /dev/mapper/funtoo-home_my
xfs

XFS cannot be shrunk.

Beyond the basics

The LVM Fun page may be of interest.

As well as these pages from Red Hat: Creating Snapshot Volumes Creating Thinly-Provionsed Logical Volumes Creating Mirrored Volumes