LVM COMMANDS

  • Initializing disks or disk partitions

    • For entire disks:

      # pvcreate /dev/sdb

    • For partitions: set the partition type to 0x8e using fdisk. Next:

      # pvcreate /dev/sdb1
pvcreate – physical volume "/dev/sdb1" successfully created

  • Creating a VG:

    # vgcreate my_VG /dev/sdb1 [/dev/sdc1] ... 

	vgcreate – INFO: using default physical extent size 4 MB (default) 

	vgcreate – INFO: maximum logical volume size is 255.99 Gigabyte

	vgcreate – doing automatic backup of volume group "my_VG" 

	vgcreate – volume group "my_VG" successfully created and activated

    # more /etc/lvmtab
	my_VG

  • Activating a VG:

    # vgchange -ay my_VG

    Note: it should be in the startup script

  • Removing a VG:

    1. Deactivate the VG: # vgchange -an my_VG

    2. Remove the VG: # vgremove my_VG

  • Adding PVs to a VG:

    # pvcreate /dev/sdb2

# vgextend my_VG /dev/sdb2

  • Removing PVs from a VG:

    # vgreduce my_VG /dev/sdb2

  • Creating an LV in my_VG:

    # lvcreate options -nmy_LV

    Main options:

    -C y/n Linear. Default is no Linear (Striped)

    -i PV_Number number of PVs to scatter the LV.

    -I S_Size Strip size (in KBytes). The strip is the transactions unit.

    -l LEs_Number number of LEs (LE size = PE size) for the new LV.

    -L LV_Size[kKmMgGtT] size for the new LV. K (kilobytes), M (megabytes), G (gigabytes) or T (terabytes). Default: M.

    -n LV_Name

    -p r/w permission

  • Creating a 1500MB linear LV named my_LV in my_VG:

    # lvcreate -Cy -L1500 -nmy_LV my_VG

  • Creating a LV of size 100 LEs (or PEs), with 2 PVs and strip size of 4 KB:

    # lvcreate -i2 -I4 -l100 -nmy_LV my_VG 

# vgdisplay my_VG

— Volume group — 

VG Name my_VG 

VG Access read/write 

VG Status available/resizable 

VG # 0 

VG Size 1.95 GB

PE Size 4 MB 

Total PE 498 

Alloc PE / Size 100 / 400 MB 

Free PE / Size 398 / 1.55 GB

  • Creating an LV that uses the entire VG, use vgdisplay to find the "Total PE" size, then use that when running lvcreate:

    # vgdisplay my_VG | grep "Total PE" 

	Total PE 10230 

# lvcreate -l10230 my_VG -nmy_LV

  • Creating an ext4 file system on the LV

    # mke4fs /dev/my_VG/my_LV

  • Mounting and Testing the File System

    # mount /dev/my_VG/my_LV /mnt/LV1 

# df

|------------------|-----------|----------|-----------|------|------------|
| Filesystem       | 1k-blocks | Used     | Available | Use% | Mounted on |
|------------------|-----------|----------|-----------|------|------------|
| /dev/hda1        | 35886784  | 13360620 | 20703192  | 40%  | /          |
| /dev/my VG/my LV | 396672    | 13       | 376179    | 1%   | /mnt/LV1   |
|------------------|-----------|----------|-----------|------|------------|

  • Obtaining LV information

    # lvdisplay /dev/my_VG/my_LV
--- Logical volume ---
LV Path                /dev/myVG/myLV
LV Name                my_LV
VG Name                my_VG
LV UUID                6Jlbd5-Mpwe-68l7-98j7-P24S-WlLx-1A1b1b
LV Write Access        read/write
LV Creation host, time hostname, YYYY-MM-DD HH:MM:SS
LV Status              available
LV Size                50.00 GiB

  • Removing a LV

    # umount /dev/my_VG/my_LV && lvremove /dev/my_VG/my_LV

Extending (+4MBs) a LV (/dev/my_VG/my_LV) mounted on /mnt/LV1:

# lvextend -L+4M /dev/my_VG/my_LV

# umount /dev/my_VG/my_LV

# e4fsck -f /dev/my_VG/my_LV

# resize4fs /dev/my_VG/my_LV

# mount /dev/my_VG/my_LV /mnt/LV1

Reducing (-4MBs) a LV (/dev/my_VG/my_LV) mounted on /mnt/LV1

# lvreduce -L-4M /dev/my_VG/my_LV

# umount /mnt/LV1

# e4fsck -f /dev/my_VG/my_LV

# resize4fs /dev/my_VG/my_LV

# mount /dev/my_VG/my_LV /mnt/LV1