# LVM
Collection of procedures for manipulating LVM stuff
# Expand VG on same partition
You want to re-use the same partition, e.g. expand sda2 and increase the size of root_pv
sda 8:0 0 50G 0 disk
├─sda1 8:1 0 487M 0 part /boot
└─sda2 8:5 0 49.5G 0 part
├─my_vg-root_pv 253:0 0 48.6G 0 lvm /
└─my_vg-swap_pv 253:1 0 980M 0 lvm [SWAP]
# Expand the VM disk
This part will be done on the hypervisor, increase the VM's disk as needed. Once the disk has been resized, use one of the methods here (opens new window) to detect the new disk size; otherwise reboot the system for it to detect the new size.
# Expand Partition Size
Install growpart to make this easier, the alternative is to delete and recreate the partition using fdisk
yum install -y cloud-utils-growpart
Expand the disk, take note of the space between /dev/sda and 2
growpart /dev/sda 2
/dev/sda2 should now show the larger size
# Resize the PV
Run pvs before and after to see the difference. You should see a larger PV after running pvresize
pvs
pvresize /dev/sda2
pvs
Your VG should also be larger now, check with
vgs
# Expand LV
This will resize your LV to take up all of the free space now available
lvextend -l +100%FREE /dev/my_vg/root_pv
# Resize Filesystem
Depending on your chosen filesystem, use one of the following:
# XFS
Using xfs:
#xfs_growfs <mountpoint>
xfs_growfs /
# EXT3/EXT4
using EXT filesystem
resize2fs /dev/my_vg/root_pv
# Expand VG using new partition
If LVM exists on partitioned areas, start with this section.
If LVM exists on bare disks, run this command (Assuming
/dev/sdais where your existing LVM resides and you just resized it):pvresize /dev/sdaOnce resized, skip to this section.
# Create or Expand the VM disk
This part will be done on the hypervisor, move on to the next part once the VM's disk has been increased in size.
# Create a new partition
Create a new partition on the newly added free space and then set the partition type to lvm
We're using /dev/sda as the disk that has been expanded
/dev/vg_vol as the existing VG to be extended
lv_part as the partition to be extended
- fdisk /dev/sda
- Create a new primary partition at /dev/sda3
n,p,3 - Check the partition table
p - Change the partition type to Linux LVM
t,3,8e - Check the partition table again
p - Write the changes
w - Reboot to save changes (if required)
# Create a new PV on the new partition
pvcreate /dev/sda3- Check the created PV
pvdisplay
# Add the new PV to the existing VG
vgextend /dev/vg_vol /dev/sda3vgdisplay
# Extend the LV to use the new space
lvextend -l +100%FREE /dev/vg_vol/lv_part
# Resize the filesystem
resize2fs /dev/vg_vol/lv_part
# Converting to LVM
We will copy our main root partition to a new empty disk and then extend the lvm partition to use the original disk after it has been copied over. This assumes that you are using a separate /boot partition.
# Prepare LVM Disk
This is our initial state:
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 1.8T 0 disk
├─sda1 8:1 0 511M 0 part /boot/efi
├─sda2 8:2 0 511M 0 part /boot
├─sda3 8:3 0 1.8T 0 part /
└─sda4 8:4 0 511M 0 part [SWAP]
sdb 8:16 0 1.8T 0 disk
└─sdb1 8:17 0 511M 0 part
We'll use /dev/sdb as our new disk for creating the LVM filesystem
vg_main as our new VG
lv_root as our new LV
- Create the new partition with
fdisk /dev/sdb
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 1.8T 0 disk
├─sda1 8:1 0 511M 0 part /boot/efi
├─sda2 8:2 0 511M 0 part /boot
├─sda3 8:3 0 1.8T 0 part /
└─sda4 8:4 0 511M 0 part [SWAP]
sdb 8:16 0 1.8T 0 disk
├─sdb1 8:17 0 511M 0 part
└─sdb2 8:18 0 1.8T 0 part
pvcreate /dev/sdb2
# pvcreate /dev/sdb2
Physical volume "/dev/sdb2" successfully created
vgcreate vg_main /dev/sdb2
# vgcreate vg_main /dev/sdb2
Volume group "vg_main" successfully created
Here's our state so far:
# vgdisplay
--- Volume group ---
VG Name vg_main
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 1.82 TiB
PE Size 4.00 MiB
Total PE 476804
Alloc PE / Size 0 / 0
Free PE / Size 476804 / 1.82 TiB
VG UUID ltBtnM-2Oxu-WVWk-YcLY-wLHy-AZiE-dm2MiR
# pvdisplay
--- Physical volume ---
PV Name /dev/sdb2
VG Name vg_main
PV Size 1.82 TiB / not usable 1.07 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 476804
Free PE 476804
Allocated PE 0
PV UUID o8svsy-NUwd-2mOe-6PWx-Taop-Cf44-MxA19c
We'll use 100% of the free space on this disk
lvcreate --name lv_root vg_main -l 100%FREE
# lvcreate --name lv_root vg_main -l 100%FREE
Logical volume "lv_root" created.
And our state:
# lvdisplay
--- Logical volume ---
LV Path /dev/vg_main/lv_root
LV Name lv_root
VG Name vg_main
LV UUID 9y6COH-813Z-AU6u-nAtd-CdCA-leOS-NgT57S
LV Write Access read/write
LV Creation host, time ns3099345, 2018-09-01 16:28:21 +0200
LV Status available
# open 0
LV Size 1.82 TiB
Current LE 476804
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:0
# Create a new filesystem
mkfs.ext4 /dev/vg_main/lv_root
# mkfs.ext4 /dev/vg_main/lv_root
mke2fs 1.42.13 (17-May-2015)
Creating filesystem with 488247296 4k blocks and 122068992 inodes
Filesystem UUID: 21a20292-bbaa-47a0-9634-138922619019
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
102400000, 214990848
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
# Copy contents to new filesystem
mkdir /mnt/sdbmount /dev/vg_main/lv_root /mnt/sdbcp -dpRx / /mnt/sdb/
# Edit fstab
We will need to add the disk in to our copied disk
- Grab UUID with
blkid
# blkid
/dev/sda1: LABEL="EFI_SYSPART" UUID="9F4B-3971" TYPE="vfat" PARTLABEL="primary" PARTUUID="cf755262-1548-4bff-9304-ea4c5cc5035d"
/dev/sda2: LABEL="/boot" UUID="1a818491-c638-4db2-988d-db2894f76d0d" TYPE="ext4" PARTLABEL="primary" PARTUUID="064c46cc-725b-4cf1-ba80-f0e194ebae99"
/dev/sda3: LABEL="/" UUID="a77a87e5-a10d-4655-b633-48676cfa3b2a" TYPE="ext4" PARTLABEL="primary" PARTUUID="fcd69399-1f5a-49fe-9d61-03d51f734e75"
/dev/sda4: LABEL="swap-sda4" UUID="68cae6eb-bc9a-42a8-ba07-91bbeb2cbb9a" TYPE="swap" PARTLABEL="primary" PARTUUID="898360d2-9b48-482c-a669-86c529d1f2af"
/dev/sdb1: LABEL="EFI_SYSPART" UUID="A00D-3109" TYPE="vfat" PARTLABEL="primary" PARTUUID="225b4983-72a6-4131-927c-9010c21382cd"
/dev/sdb2: UUID="o8svsy-NUwd-2mOe-6PWx-Taop-Cf44-MxA19c" TYPE="LVM2_member" PARTUUID="a49e995c-a690-4b35-98cf-865047688ad3"
/dev/mapper/vg_main-lv_root: UUID="21a20292-bbaa-47a0-9634-138922619019" TYPE="ext4"
nano /mnt/sdb/etc/fstab
Add UUID= to the UUID itself and place it in the file
This is what the result looks like:
# <file system> <mount point> <type> <options> <dump> <pass>
#/dev/sda3 / ext4 errors=remount-ro,relatime 0 1
UUID=21a20292-bbaa-47a0-9634-138922619019 / ext4 errors=remount-ro,relatime 0 1
/dev/sda2 /boot ext4 errors=remount-ro,relatime 0 1
/dev/sda4 swap swap defaults 0 0
proc /proc proc defaults 0 0
sysfs /sys sysfs defaults 0 0
/dev/sda1 /boot/efi vfat defaults,relatime 0 0
devtmpfs /dev devtmpfs rw 0 0
# Scan the changes
vgscanvgchange -ay
# vgscan
Reading all physical volumes. This may take a while...
Found volume group "vg_main" using metadata type lvm2
# vgchange -ay
1 logical volume(s) in volume group "vg_main" now active
# Create new ramdisk
This step may be needed if your existing ramdisk is not aware of LVM
mkinitramfs -o /boot/initrd-$(uname -r).lvm.img
# mkinitramfs -o /boot/initrd-$(uname -r).lvm.img
W: mdadm: /etc/mdadm/mdadm.conf defines no arrays.
# ls -lah /boot
total 85M
drwxr-xr-x 4 root root 1.0K Sep 1 16:35 .
drwxr-xr-x 21 root root 4.0K Sep 1 16:04 ..
-rw-r--r-- 1 root root 1.2M Aug 15 19:48 abi-4.4.0-134-generic
-rw-r--r-- 1 root root 187K Aug 15 19:48 config-4.4.0-134-generic
drwxr-xr-x 3 root root 4.0K Jan 1 1970 efi
drwxr-xr-x 6 root root 1.0K Sep 1 15:58 grub
-rw-r--r-- 1 root root 37M Sep 1 16:35 initrd-4.4.0-134-generic.lvm.img
-rw-r--r-- 1 root root 37M Sep 1 16:04 initrd.img-4.4.0-134-generic
-rw-r--r-- 1 root root 255 Aug 15 19:48 retpoline-4.4.0-134-generic
-rw------- 1 root root 3.8M Aug 15 19:48 System.map-4.4.0-134-generic
-rw------- 1 root root 6.9M Aug 15 19:48 vmlinuz-4.4.0-134-generic
# Edit grub
nano /boot/grub/grub.cfg- Add
/dev/vg_main/lv_rootto the root directory - Change initrd image to the one created earlier
mkinitramfs -o /boot/initrd-$(uname -r).lvm.img
Result
---snip---
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-a77a87e5-a10d-4655-b633-48676cfa3b2a' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 1a818491-c638-4db2-988d-db2894f76d0d
else
search --no-floppy --fs-uuid --set=root 1a818491-c638-4db2-988d-db2894f76d0d
fi
linux /vmlinuz-4.4.0-134-generic root=/dev/vg_main/lv_root ro noquiet nosplash net.ifnames=0 biosdevname=0
initrd /initrd-4.4.0-134-generic.lvm.img
---snip---
# Reboot
Check that your server comes back up, once it does, it should look like this:
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 1.8T 0 disk
├─sda1 8:1 0 511M 0 part /boot/efi
├─sda2 8:2 0 511M 0 part /boot
├─sda3 8:3 0 1.8T 0 part
└─sda4 8:4 0 511M 0 part [SWAP]
sdb 8:16 0 1.8T 0 disk
├─sdb1 8:17 0 511M 0 part
└─sdb2 8:18 0 1.8T 0 part
└─vg_main-lv_root 252:0 0 1.8T 0 lvm /
# df -h
Filesystem Size Used Avail Use% Mounted on
udev 16G 0 16G 0% /dev
tmpfs 3.2G 14M 3.1G 1% /run
/dev/vg_main/lv_root 1.8T 1.5G 1.7T 1% /
tmpfs 16G 0 16G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/sda2 487M 97M 362M 22% /boot
/dev/sda1 510M 136K 510M 1% /boot/efi
You can see that the / partition is mounted on /dev/sdb2 now.
# Create New PV
- Check your disk layout
fdisk -lorlsblk
DANGER
Do not delete your boot partition!
pvcreate /dev/sda3
# pvcreate /dev/sda3
WARNING: ext4 signature detected on /dev/sda3 at offset 1080. Wipe it? [y/n]: y
Wiping ext4 signature on /dev/sda3.
Physical volume "/dev/sda3" successfully created
- Check the new PV
pvdisplay
# pvdisplay
--- Physical volume ---
PV Name /dev/sdb2
VG Name vg_main
PV Size 1.82 TiB / not usable 1.07 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 476804
Free PE 0
Allocated PE 476804
PV UUID o8svsy-NUwd-2mOe-6PWx-Taop-Cf44-MxA19c
"/dev/sda3" is a new physical volume of "1.82 TiB"
--- NEW Physical volume ---
PV Name /dev/sda3
VG Name
PV Size 1.82 TiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID 3uJ1oO-kt5i-cjnR-kHU8-1jOc-1jzx-Wa1gXj
# Extend VG
- Extend your VG
vgextend /dev/vg_main /dev/sda3
# vgextend /dev/vg_main /dev/sda3
Volume group "vg_main" successfully extended
- Check your VG
vgdisplay
# vgdisplay
--- Volume group ---
VG Name vg_main
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 2
Act PV 2
VG Size 3.64 TiB
PE Size 4.00 MiB
Total PE 953351
Alloc PE / Size 476804 / 1.82 TiB
Free PE / Size 476547 / 1.82 TiB
VG UUID ltBtnM-2Oxu-WVWk-YcLY-wLHy-AZiE-dm2MiR
# Extend LV
- Extend your LV
lvextend -l +100%FREE /dev/vg_main/lv_root
# lvextend -l +100%FREE /dev/vg_main/lv_root
Size of logical volume vg_main/lv_root changed from 1.82 TiB (476804 extents) to 3.64 TiB (953351 extents).
Logical volume lv_root successfully resized.
- Check your LV
lvs
# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv_root vg_main -wi-ao---- 3.64t
# lvdisplay
--- Logical volume ---
LV Path /dev/vg_main/lv_root
LV Name lv_root
VG Name vg_main
LV UUID 9y6COH-813Z-AU6u-nAtd-CdCA-leOS-NgT57S
LV Write Access read/write
LV Creation host, time ns3099345, 2018-09-01 16:28:21 +0200
LV Status available
# open 1
LV Size 3.64 TiB
Current LE 953351
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:0
# Resizing the filesystem
- Resize the partition
resize2fs /dev/vg_main/lv_rootBefore:
# df -h
Filesystem Size Used Avail Use% Mounted on
udev 16G 0 16G 0% /dev
tmpfs 3.2G 14M 3.1G 1% /run
/dev/vg_main/lv_root 1.8T 1.5G 1.7T 1% /
tmpfs 16G 0 16G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/sda2 487M 97M 362M 22% /boot
/dev/sda1 510M 136K 510M 1% /boot/efi
# resize2fs /dev/vg_main/lv_root
resize2fs 1.42.13 (17-May-2015)
Filesystem at /dev/vg_main/lv_root is mounted on /; on-line resizing required
old_desc_blocks = 117, new_desc_blocks = 233
The filesystem on /dev/vg_main/lv_root is now 976231424 (4k) blocks long.
After:
# df -h
Filesystem Size Used Avail Use% Mounted on
udev 16G 0 16G 0% /dev
tmpfs 3.2G 14M 3.1G 1% /run
/dev/vg_main/lv_root 3.6T 1.5G 3.5T 1% /
tmpfs 16G 0 16G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/sda2 487M 97M 362M 22% /boot
/dev/sda1 510M 136K 510M 1% /boot/efi
# Finish
Reboot your system to make sure everything comes back.
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