# Filesystem

# Expanding an existing filesystem using LVM

##### Description

This example below shows you how to expand an existing filesystem that it managed by Logical Volume Manager (LVM)

#### Examine the existing filesystem

This command will to the host to rescan the host adapters after a new disk has been added.

> echo "- - -" | tee /sys/class/scsi\_host/host\*/scan

/dev/mapper/ubuntu--vg-ubuntu--lv is the filesystem I want to expand.

> root@dock-host-2:/mnt# df -lh  
> Filesystem Size Used Avail Use% Mounted on  
> tmpfs 1.6G 1.7M 1.6G 1% /run  
> /dev/mapper/ubuntu--vg-ubuntu--lv 63G 17G 43G 28% /  
> tmpfs 7.9G 0 7.9G 0% /dev/shm  
> tmpfs 5.0M 0 5.0M 0% /run/lock  
> /dev/sda2 974M 163M 745M 18% /boot  
> tmpfs 1.6G 4.0K 1.6G 1% /run/user/1000

Use lsblk to take a look at all devices available. In my example I am going to use /dev/sdb as the disk to expand the existing filesystem in the LVM. lsblk shows that is /dev/sdb is 128GB in size.

> root@dock-host-2:~# lsblk  
> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT  
> loop0 7:0 0 55.5M 1 loop /snap/core18/2344  
> loop1 7:1 0 55.5M 1 loop /snap/core18/2409  
> loop2 7:2 0 118.4M 1 loop /snap/docker/1779  
> loop3 7:3 0 61.9M 1 loop /snap/core20/1494  
> loop4 7:4 0 102.4M 1 loop /snap/lxd/23243  
> loop5 7:5 0 61.9M 1 loop /snap/core20/1518  
> loop6 7:6 0 117.2M 1 loop /snap/docker/1767  
> loop7 7:7 0 47M 1 loop /snap/snapd/16292  
> loop8 7:8 0 47M 1 loop /snap/snapd/16010  
> loop10 7:10 0 102.4M 1 loop /snap/lxd/23270  
> sda 8:0 0 128G 0 disk  
> ├─sda1 8:1 0 1M 0 part  
> ├─sda2 8:2 0 1G 0 part /boot  
> └─sda3 8:3 0 127G 0 part  
>  └─ubuntu--vg-ubuntu--lv 253:0 0 63.5G 0 lvm /  
> sdb 8:16 0 128G 0 disk  
> sr0 11:0 1 1024M 0 rom

The next step is to run a command to prep the new disk for the LVM format.

> root@dock-host-2:~# pvcreate /dev/sdb  
> WARNING: dos signature detected on /dev/sdb at offset 510. Wipe it? \[y/n\]: y  
>  Wiping dos signature on /dev/sdb.  
>  Physical volume "/dev/sdb" successfully created.

Once the disk is ready we need to identify the the LVM name and use it to extend the volume with the new disk we set up.

> root@dock-host-2:~# vgs  
>  VG #PV #LV #SN Attr VSize VFree  
>  ubuntu-vg 1 1 0 wz--n- <127.00g 63.50g

Once we know the name of the Volume Group we can expand the Volume Group with the new disk.

> root@dock-host-2:~# vgextend ubuntu-vg /dev/sdb  
>  Volume group "ubuntu-vg" successfully extended

After the Volume Group has been extended we can run some commands to verify the new size. You can see in the example below that we have more space in our Volume Group.

> root@dock-host-2:~# vgs  
>  VG #PV #LV #SN Attr VSize VFree  
>  ubuntu-vg 2 1 0 wz--n- 254.99g <191.50g
> 
> root@dock-host-2:~# vgdisplay  
> \--- Volume group ---  
>  VG Name ubuntu-vg  
>  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 254.99 GiB  
>  PE Size 4.00 MiB  
>  Total PE 65278  
>  Alloc PE / Size 16255 / <63.50 GiB  
>  Free PE / Size 49023 / <191.50 GiB  
>  VG UUID CVE1jf-w4fj-FreW-Xn1p-i3gv-gzbh-GcpJdY

Now that the Volume Group is expanded we need to expand the Logical Volume and expand the Filesystem to use the new disk space. The commands below are used to check on the Logical Volume and then extend the Logical Volume.

> root@dock-host-2:~# lvdisplay  
> \--- Logical volume ---  
>  LV Path /dev/ubuntu-vg/ubuntu-lv  
>  LV Name ubuntu-lv  
>  VG Name ubuntu-vg  
>  LV UUID K5CEFt-q6tF-cjxB-wCFh-f970-CTy9-07KYYk  
>  LV Write Access read/write  
>  LV Creation host, time ubuntu-server, 2021-12-19 20:48:29 +0000  
>  LV Status available  
>  # open 1  
>  LV Size <63.50 GiB  
>  Current LE 16255  
>  Segments 1  
>  Allocation inherit  
>  Read ahead sectors auto  
> \- currently set to 256  
>  Block device 253:0

> root@dock-host-2:~# lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv  
>  Size of logical volume ubuntu-vg/ubuntu-lv changed from <63.50 GiB (16255 extents) to 254.99 GiB (65278 extents).  
>  Logical volume ubuntu-vg/ubuntu-lv successfully resized.

The last step is the expand the filesystem and verify that there is more free space.

> root@dock-host-2:~# resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv  
> resize2fs 1.46.3 (27-Jul-2021)  
> Filesystem at /dev/mapper/ubuntu--vg-ubuntu--lv is mounted on /; on-line resizing required  
> old\_desc\_blocks = 8, new\_desc\_blocks = 32  
> The filesystem on /dev/mapper/ubuntu--vg-ubuntu--lv is now 66844672 (4k) blocks long.

> root@dock-host-2:~# df -lh  
> Filesystem Size Used Avail Use% Mounted on  
> tmpfs 1.6G 1.7M 1.6G 1% /run  
> /dev/mapper/ubuntu--vg-ubuntu--lv 251G 17G 224G 7% /  
> tmpfs 7.9G 0 7.9G 0% /dev/shm  
> tmpfs 5.0M 0 5.0M 0% /run/lock  
> /dev/sda2 974M 163M 745M 18% /boot  
> tmpfs 1.6G 4.0K 1.6G 1% /run/user/1000