Features:
1. Ability to create volume sets and stripe sets
2. LVM masks the underlying physical technology (ATA,ATAPI,IDE,SCSI,SATA,PATA,etc.)
3. LVM represents storage using a hierarchy:
• Volume groups
a1. Physical volumes (/dev/sda2, /dev/sdb2, etc.)
• b. Logical Volumes
b1. File systems
4. LVM physical volumes can be of various sizes
5. Ability to resize volumes on the fly
Note: Volume groups join: physical volumes (PVs) and Logical Volumes (LVs)
6 Steps to setup LVM:
1. Create LVM partitions via fdisk or parted
• fdisk /dev/sda, /dev/sdb, /dev/sdc
• n
• p
• +10G
• t - change to type '8e' (LVM)
• w
• partprobe /dev/sda
2. Create Physical Volumes using 'pvcreate'
• pvcreate /dev/sda3 /dev/sdb3 /dev/sdc3
3. Create Volume Groups using 'vgcreate'
• vgcreate volgroup001 /dev/sda3 /dev/sdb3 /dev/sdc3
Note: Volume groups can be segmented into multiple logical volumes
4. Create one or more Logical Volumes
• lvcreate -L 10GB -n logvolvar1 volgroup001
• b. lvcreate -L 10GB -n logvolusr1 volgroup001
5. Create File system on logical volume(s)
• mke2fs -j /dev/volgroup001/logvolvar1
• b. mke2fs -j /dev/volgroup001/logvolusr1
6. Mount logical volume
• mkdir /var1
• mount /dev/volgroup001/logvolvar1 /var1
• mkdir /usr1
• mount /dev/volgroup001/logvolusr1 /usr1
Note: Be certain to update: /etc/fstab so that volumes are mounted when the system reboots
3-tiers of LVM display commands include:
• pvdisplay - physical volumes - represent raw LVM partitions
• vgdisplay - volume groups - aggregate physical volumes
• lvdisplay - logical volumes - file systems - mount here
Rename of Logical Volume:
1. lvrename volume_group_name old new - used to rename volumes
Task:
Rename 'logvolvar1' to 'logvolopt1'
• lvrename volgroup001 logvolvar1 logvolopt1
Note: LVM is updated immediately, even while volume is mounted
However, you must remount the logical volume to see the changes
• b. umount /var1 && mount /dev/mapper/volgroup001-logvolopt1 /opt1
• c. Update /etc/fstab
Remove Logical Volume:
Task:
Remove 'logvolusr1' from the logical volume pool
• umount /usr1
• lvremove /dev/mapper/volgroup001-logvolusr1
• use 'lvdisplay' to confirm removal
Resize Logical Volume:
Task:
Grow (resize) 'logvolopt1' to 20GB
• lvresize -L 20GB /dev/volgroup001/logvolopt1
• lvdisplay - to confirm new size of logical volume
• df -h - will still reveal the current size
• Resize the file system to update the INODE table on the logical volume to account for the new storage in 'logvolopt1'
'resize2fs -f -p /dev/volgroup001/logvolopt1'
Note: You may resize file systems online if the following are met:
2.6x kernel series
MUST be formatted with ext3
Task:
Shrink (resize) 'logvolopt1' to 15GB
• lvresize -L 15GB /dev/volgroup001/logvolopt1
• lvdisplay
• df -h
• resize2fs -f -p /dev/volgroup001/logvolopt1
Note: online shrinking is not supported
• e. df -h
Note: Check disk utilization prior to shrinking to reduce the risk of losing data
LVM GUI utility:
• system-config-lvm