LVM allows you to create, resize or delete partitions on a running system without requiring any reboot. So check the steps below to extend root filesystem using LVM in Linux. You can skip some steps which don’t apply to use.
Step 1: Confirm Disk Partitions in Distribution.
Before we can do any extension, let’s just confirm our disk layout / partitioning scheme.
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sr0 11:0 1 1024M 0 rom
vda 252:0 0 30G 0 disk
├─vda1 252:1 0 1G 0 part /boot
└─vda2 252:2 0 29G 0 part
├─rhel-root 253:0 0 26.9G 0 lvm /
└─rhel-swap 253:1 0 2.1G 0 lvm [SWAP]
As noted, we have a root filesystem on /dev/vda2 physical volume.
$ sudo pvs
PV VG Fmt Attr PSize PFree
/dev/vda2 rhel lvm2 a-- <29.00g 0
Step 2: Extend your OS root disk
As shown in step 1, my root filesystem is on a 30GB disk. I’ll grow it to 40GB by extending the virtual disk (VM disk device).
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sr0 11:0 1 1024M 0 rom
vda 252:0 0 40G 0 disk
├─vda1 252:1 0 1G 0 part /boot
└─vda2 252:2 0 29G 0 part
├─rhel-root 253:0 0 26.9G 0 lvm /
└─rhel-swap 253:1 0 2.1G 0 lvm [SWAP]
Once the OS block device is resized, ssh to your Linux machine and extend LVM to use newly added disk capacity. The command below will expand the last partition (Partition 2), as shown by 252:2,on the disk (/dev/vda) to the maximum size the disk provides.
Install cloud utils package on the system
For those new to growpart, it is a Linux command line tool used to extend a partition in a partition table to fill available space. This command is provided by cloud utils package.
On Ubuntu / Debian system, run the commands below to install growpart tool.
$ sudo apt install cloud-guest-utils
For CentOS server, run
$ sudo yum -y install cloud-utils-growpart
Help page can be viewed by passing -h
argument
$ growpart -h
growpart disk partition
rewrite partition table so that partition takes up all the space it can
options:
-h | --help print Usage and exit
--fudge F if part could be resized, but change would be
less than 'F' bytes, do not resize (default: 1048576)
-N | --dry-run only report what would be done, show new 'sfdisk -d'
-v | --verbose increase verbosity / debug
-u | --update R update the the kernel partition table info after growing
this requires kernel support and 'partx --update'
R is one of:
- 'auto' : [default] update partition if possible
- 'force' : try despite sanity checks (fail on failure)
- 'off' : do not attempt
- 'on' : fail if sanity checks indicate no support
Example:
- growpart /dev/sda 1
Resize partition 1 on /dev/sd
Now use growpart to extend your partition. In this example we’re extending partition 2 in disk /dev/vda. Replace 2 and /dev/vda with your correct values.
$ sudo growpart /dev/vda 2
CHANGED: partition=2 start=2099200 old: size=18872320 end=20971520 new: size=60815327,end=62914527
Confirm if the change was successful.
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sr0 11:0 1 1024M 0 rom
vda 252:0 0 40G 0 disk
├─vda1 252:1 0 1G 0 part /boot
└─vda2 252:2 0 39G 0 part
├─rhel-root 253:0 0 26.9G 0 lvm /
└─rhel-swap 253:1 0 2.1G 0 lvm [SWAP]
Step 3: Resize root logical volume to occupy all space
Resize physical volume.
$ pvresize -v /dev/vda2
Physical volume "/dev/vda2" changed
1 physical volume(s) resized or updated / 0 physical volume(s) not resized
$ sudo pvs
PV VG Fmt Attr PSize PFree
/dev/vda2 rhel lvm2 a-- <39.00g 10.00g
Check the size of the volume group configured.
$ sudo vgs
VG #PV #LV #SN Attr VSize VFree
rhel 1 2 0 wz--n- <39.00g 10.00g
Then resize logical volume used by the root file system using the extended volume group:
sudo lvextend -r -l +100%FREE /dev/name-of-volume-group/root
This extends the logical volume to use all available capacity in the volume group. With the + sign the value is added to the actual size of the logical volume.
Command options used:
- -l – extend or set the logical volume size in units of logical extents
- -r – Resize underlying filesystem together with the logical volume
Here’s an example of my setup file system extension:
$ df -hT | grep mapper
/dev/mapper/rhel-root xfs 27G 1.9G 26G 8% /
$ sudo lvextend -r -l +100%FREE /dev/mapper/rhel-root
Size of logical volume rhel/root changed from <26.93 GiB (6893 extents) to <36.93 GiB (9453 extents).
Logical volume rhel/root successfully resized.
If you prefer setting the size to be extended manually, use command option:
-L, --size [+]LogicalVolumeSize[bBsSkKmMgGtTpPeE]
Where size suffix are:
- M for megabytes
- G for gigabytes
- T for terabytes
- P for petabytes
- E for exabytes
Without the + sign the value is taken as an absolute one.
# Add 20 gigabytes to the current logical volume size
$ sudo lvextend -r -L +20G /dev/name-of-volume-group/root
Step 4: Update changes on the filesystem (If you didn’t use -r option in step 3)
Your root filesystem will still show the old size.
$ df -hT | grep mapper
/dev/mapper/rhel-root xfs 27G 1.9G 26G 8% /
Let’s make the filesystem report the actual size, including extended.
For ext4 filesystem
sudo resize2fs /dev/name-of-volume-group/root
For xfs filesystem
$ sudo xfs_growfs /
meta-data=/dev/mapper/rhel-root isize=512 agcount=4, agsize=1764608 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=1
data = bsize=4096 blocks=7058432, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=3446, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 7058432 to 9679872
Conclusion
You have learned how to extend root filesystem backed by nfs and ext4 with this how to extend root filesystem using LVM guide. We hope this was helpful and would like to thank you for reading.