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Extend LVM Logical Volume

How to extend a LVM logical volume.

Extend the physical drive.

gcloud compute disks resize data-drive --size=40GB

SSH to a server and extend the physical volume.

$ pvresize /dev/sdb
  Physical volume "/dev/sdb" changed
  1 physical volume(s) resized or updated / 0 physical volume(s) not resized
$ pvs
  PV         VG Fmt  Attr PSize   PFree 
  /dev/sdb   vg lvm2 a--  <40.00g 10.00g
$ vgs
  VG #PV #LV #SN Attr   VSize   VFree 
  vg   1   1   0 wz--n- <40.00g 10.00g
$ lvs
  LV   VG Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  data vg -wi-ao---- <30.00g

Extend the logical volume.

$ lvresize -l +100%FREE /dev/vg/data
  Size of logical volume vg/data changed from <30.00 GiB (7679 extents) to <40.00 GiB (10239 extents).
  Logical volume vg/data successfully resized.

Check the volume size.

$ lsblk
NAME      MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda         8:0    0   20G  0 disk 
├─sda1      8:1    0  200M  0 part /boot/efi
└─sda2      8:2    0 19.8G  0 part /
sdb         8:16   0   40G  0 disk 
└─vg-data 253:0    0   40G  0 lvm  /mnt

Still at 30GB.

$ df -Th
Filesystem          Type      Size  Used Avail Use% Mounted on
devtmpfs            devtmpfs  385M     0  385M   0% /dev
tmpfs               tmpfs     403M     0  403M   0% /dev/shm
tmpfs               tmpfs     403M  5.5M  398M   2% /run
tmpfs               tmpfs     403M     0  403M   0% /sys/fs/cgroup
/dev/sda2           xfs        20G  2.9G   17G  15% /
/dev/sda1           vfat      200M  5.8M  195M   3% /boot/efi
/dev/mapper/vg-data xfs        30G  247M   30G   1% /mnt
tmpfs               tmpfs      81M     0   81M   0% /run/user/1001

Extend the file system.

$ xfs_growfs /dev/vg/data
meta-data=/dev/mapper/vg-data    isize=512    agcount=12, agsize=655360 blks
         =                       sectsz=4096  attr=2, projid32bit=1
         =                       crc=1        finobt=1, sparse=1, rmapbt=0
         =                       reflink=1
data     =                       bsize=4096   blocks=7863296, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=4096  sunit=1 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 7863296 to 10484736

Let’s check again.

$ df -Th
Filesystem          Type      Size  Used Avail Use% Mounted on
devtmpfs            devtmpfs  385M     0  385M   0% /dev
tmpfs               tmpfs     403M     0  403M   0% /dev/shm
tmpfs               tmpfs     403M  5.5M  398M   2% /run
tmpfs               tmpfs     403M     0  403M   0% /sys/fs/cgroup
/dev/sda2           xfs        20G  2.9G   17G  15% /
/dev/sda1           vfat      200M  5.8M  195M   3% /boot/efi
/dev/mapper/vg-data xfs        40G  319M   40G   1% /mnt
tmpfs               tmpfs      81M     0   81M   0% /run/user/1001

The logical volume is now at 40GB.

Setup LVM on a VM

How to setup Logical Volume Manager on a VM.

Install LVM.

yum install lvm2

Check the disks available. We are going to run LVM on /dev/sdb.

$ lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0   20G  0 disk 
├─sda1   8:1    0  200M  0 part /boot/efi
└─sda2   8:2    0 19.8G  0 part /
sdb      8:16   0   20G  0 disk

Create a physical volume on /dev/sdb.

$ pvcreate /dev/sdb
  Physical volume "/dev/sdb" successfully created.
$ pvs
  PV         VG Fmt  Attr PSize   PFree
  /dev/sdb   vg lvm2 a--  <20.00g    0

Create a volume group called vg.

$ vgcreate vg /dev/sdb
  Volume group "vg" successfully created
$ vgs
  VG #PV #LV #SN Attr   VSize   VFree  
  vg   1   0   0 wz--n- <20.00g <20.00g

Create a 10GB logical volume group called data.

$ lvcreate -L 10G -n data vg
  Logical volume "data" created.
$ lvs
  LV   VG Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  data vg -wi-a----- 10.00g

Format the volume group and mount it.

$ mkfs.xfs /dev/vg/data
meta-data=/dev/vg/data           isize=512    agcount=4, agsize=655360 blks
         =                       sectsz=4096  attr=2, projid32bit=1
         =                       crc=1        finobt=1, sparse=1, rmapbt=0
         =                       reflink=1
data     =                       bsize=4096   blocks=2621440, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=4096  sunit=1 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
Discarding blocks...Done.
$ mount /dev/vg/data /mnt

Check your logical volume. It says 10GB.

$ df -Th
Filesystem          Type      Size  Used Avail Use% Mounted on
devtmpfs            devtmpfs  385M     0  385M   0% /dev
tmpfs               tmpfs     403M     0  403M   0% /dev/shm
tmpfs               tmpfs     403M  5.5M  398M   2% /run
tmpfs               tmpfs     403M     0  403M   0% /sys/fs/cgroup
/dev/sda2           xfs        20G  2.9G   17G  15% /
/dev/sda1           vfat      200M  5.8M  195M   3% /boot/efi
tmpfs               tmpfs      81M     0   81M   0% /run/user/1000
/dev/mapper/vg-data xfs        10G  104M  9.9G   2% /mnt

Let’s now extend the logical volume to 20GB.

$ lvextend -l +100%FREE /dev/vg/data
  Size of logical volume vg/data changed from 10.00 GiB (2560 extents) to <20.00 GiB (5119 extents).
  Logical volume vg/data successfully resized.

Although lsblk says 20GB, our logical volume still says 10GB.

$ lsblk
NAME      MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda         8:0    0   20G  0 disk 
├─sda1      8:1    0  200M  0 part /boot/efi
└─sda2      8:2    0 19.8G  0 part /
sdb         8:16   0   20G  0 disk 
└─vg-data 253:0    0   20G  0 lvm  /mnt
$ df -Th
Filesystem          Type      Size  Used Avail Use% Mounted on
devtmpfs            devtmpfs  385M     0  385M   0% /dev
tmpfs               tmpfs     403M     0  403M   0% /dev/shm
tmpfs               tmpfs     403M  5.5M  398M   2% /run
tmpfs               tmpfs     403M     0  403M   0% /sys/fs/cgroup
/dev/sda2           xfs        20G  2.9G   17G  15% /
/dev/sda1           vfat      200M  5.8M  195M   3% /boot/efi
tmpfs               tmpfs      81M     0   81M   0% /run/user/1000
/dev/mapper/vg-data xfs        10G  104M  9.9G   2% /mnt

We need to grow the file system.

$ xfs_growfs /dev/vg/data
meta-data=/dev/mapper/vg-data    isize=512    agcount=4, agsize=655360 blks
         =                       sectsz=4096  attr=2, projid32bit=1
         =                       crc=1        finobt=1, sparse=1, rmapbt=0
         =                       reflink=1
data     =                       bsize=4096   blocks=2621440, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=4096  sunit=1 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 2621440 to 5241856

Let’s check again.

$ df -Th
Filesystem          Type      Size  Used Avail Use% Mounted on
devtmpfs            devtmpfs  385M     0  385M   0% /dev
tmpfs               tmpfs     403M     0  403M   0% /dev/shm
tmpfs               tmpfs     403M  5.5M  398M   2% /run
tmpfs               tmpfs     403M     0  403M   0% /sys/fs/cgroup
/dev/sda2           xfs        20G  2.9G   17G  15% /
/dev/sda1           vfat      200M  5.8M  195M   3% /boot/efi
tmpfs               tmpfs      81M     0   81M   0% /run/user/1000
/dev/mapper/vg-data xfs        20G  176M   20G   1% /mnt

It now says 20GB.

LVM Extend Physical Volume

The following are instructions on how to extend a disk volume with LVM.

# aws cli extend volume
aws ec2 modify-volume --region us-east-1 \
--volume-id vol-xxxxxxxxxxxx --size 15 \
--volume-type gp2
# check volumes before
lsblk
# extend via growpart
growpart /dev/xvdf 1
# check volumes after
lsblk
# resize physical volume
pvresize /dev/xvdf1
# check physical volume
pvscan
# extend logical volume
lvresize -l +100%FREE /dev/data/data
# check logical volume
lvscan
# check mounts
df -Th
# resize file system
resize2fs /dev/data/data
# or
xfs_growfs /dev/mapper/root
xfs_growfs /dev/xvda1
# check mounts again for new size
df -Th

Extend LVM volume

Extending a LVM logical volume can be tricky. Extending a physical volume especially a boot drive is even more challenging. To make things simple, you can just easily add a new physical disk to your physical volume group. Here are the steps:

# add disk to your instance. 
fdisk /dev/sdh
pvcreate /dev/sdh1
vgextend system /dev/sdh1
lvextend -l +100%FREE /dev/system/opt
resize2fs /dev/system/opt

The fdisk command requires a few steps inside such as creating a new partition, changing the partition to type to “8e” which is Linux LVM, and then writing your changes to disk.

The rest are pretty much self explanatory. It’s about creating a physical volume, extending the volume group, extending the logical volume, and then finally resizing the file system.