###Logical Volume Management (LVM)###
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:
a. Volume Groups (VG)
a1. Physical Volumes (PV) (/dev/sda2, /dev/sdb2, etc.)
b. Logical Volumes (LV)
b1. File system
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)
Steps to setup LVM:
1. Create LVM partitions via fdisk or parted
a. ''fdisk /dev/sda, /dev/sdb, /dev/sdc
b. n
c. p
d. 10G
e. t - change to type ''8e'' (LVM)
f. w
g. partprobe /dev/sda
2. Create Physical Volumes using ''pvcreate''
a. pvcreate /dev/sda3 /dev/sdb3 /dev/sdc3
3. Create Volume Groups using ''vgcreate''
a. 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
a. lvcreate -L 10GB -n logvolvar1 volgroup001
b. lvcreate -L 10GB -n logvolusr1 volgroup001
5. Create File system on Logical Volume(s)
a. ''mke2fs -j /dev/volgroup001/logvolvar1''
b. ''mke2fs -j /dev/volgroup001/logvolusr1''
6. Mount Logical Volume
a. mkdir /var1
b. ''mount /dev/volgroup001/logvolvar1 /var1
c. mkdir /usr1
d. ''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:
a. pvdisplay - physical volumes - represent raw LVM partitions
b. vgdisplay - volume groups - aggregate physical volumes
c. lvdisplay - logical volumes - file systems - mount here
Rename of Logical Volumes
1. lvrename - used to rename volumes
a. lvrename volume_group_name old new
Task: Rename ''logvolvar1'' to ''logvolopt1''
a. lvrename volgroup001 logvolvar1 logvolopt1
Note: LVM is updated immediately, even while volume is mounted
Note: However, you must remount the logical volume to see the changes
b. umount /var1 && mount /dev/mapper/volgroup001-logvolopt1 /opt1
c. Update /etc/fstab
Note: /dev/volgroup001/* is symlinks to /dev/mapper/
Remove Logical Volumes
Task: remove ''logvolusr1'' from the logical volume pool
a. umount /usr1
b. lvremove /dev/mapper/volgroup001-logvolusr1
c. use ''lvdisplay'' to confirm removal
Resize Logical Volume:
Task: Grow (resize) ''logvolopt1'' to 20GB
a. lvresize -L 20GB /dev/volgroup001/logvolopt1
b. lvdisplay - to confirm new size of logical volume
c. df -h - will still reveal the current size
d. Resize the file system to update the INODE table on the logical volume to account for the new storage in ''logvolopt1''
d1. ''resize2fs -f -p /dev/volgroup001/logvolopt1''
Note: You may resize file systems online if the following are met:
1. 2.6x kernel series
2. MUST be formatted with ext3
Task: Shrink (resize) ''logvolopt1'' to 15GB
a. lvresize -L 15GB /dev/volgroup001/logvolopt1
b. lvdisplay
c. df -h
d. 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
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