LVM

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Note: These instructions are for RHEL/CentOS unless otherwise specified

Also see: http://www.centos.org/docs/5/html/Cluster_Logical_Volume_Manager/

The structure looks kind of like this:

  • partition/physical volume
    • volume group
      • logical volume
        • filesystem (ex: ext3)

Creating LVMs

Create a partition for use with lvm

Use fdisk

fdisk /dev/sdb
  • n (add a new partition)
  • t (change type)
  • 8e (for linux LVM)
  • p (print partition table)
  • w (write)

Show physical volumes

sudo pvdisplay

Initialize physical volume

sudo pvcreate /dev/sdb1

Show volume groups

sudo vgdisplay

Create volume group

sudo vgcreate VolGroup00 /dev/sdb1

Show all logical volumes

sudo lvdisplay

Show logical volumes in a volume group

sudo lvdisplay -v VolGroup00

Create new 40G logical volume

sudo lvcreate -L 40G -n LogVol07 VolGroup00

Create a new logical volume that uses 100% of the volume group space

sudo lvcreate -l 100%VG -n LogVol00 VolGroup01

Create a new logical volume that uses 100% of the free space in the volume group

sudo lvcreate -l 100%FREE -n LogVol00 VolGroup01

Format a filesystem

ext4:

sudo mkfs.ext4 /dev/mapper/VolGroup01-LogVol07

ext3:

sudo mke2fs -j /dev/mapper/VolGroup01-LogVol07

Put in fstab

/dev/VolGroup00/LogVol07 /u01                    ext4    defaults        1 2
/dev/VolGroup00/LogVol07 /u01                    ext3    defaults        1 2

Create the directory

sudo mkdir /u01

Mount

sudo mount -a

Or:

sudo mount /u01

Removing LVMs

  1. Unmount the filesystem

    sudo umount /u01

  2. Remove the LVM

    sudo lvremove /dev/mapper/VolGroup01-LogVol00

  3. Remove the volume group

    sudo vgremove VolGroup01

  4. Remove the physical volume/partition

    sudo pvremove /dev/sdb1

  5. Delete the partition table

    1. sudo fdisk /dev/sdb
    2. Press p to show the partition table
    3. Press d to delete the partition
    4. Press p to show the partition table
    5. Press w to write the partition table and quit

Growing LVMs (and the filesystems they contain)

  1. Unmount the filesystem

    sudo umount /u01

  2. Grow the lvm

    sudo lvextend -L80G /dev/VolGroup00/LogVol07

  3. Check the filesystem for errors

    sudo e2fsck -f /dev/VolGroup00/LogVol07

  4. Resize the filesystem

    sudo resize2fs /dev/VolGroup00/LogVol07