Linux/VM: Sample LVM Scripts

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Sunday, July 06, 2008

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Sample LVM Scripts

This information was contributed by Jim Sibley on June 28, 2002. A similar example can be found in Chapter 17 of the Linux for zSeries and S/390: Distributions, SG24-6264 Redbook.

Details of each command can be found using the man command.

The 7 scripts below show the 7 steps in implementing an LVM volume group with four (4) logical 8 GB volumes striped over 16 physical volumes.

vgscan initializes LVM and looks for existing LVM structures
pvcreate creates LVM physical volumes
vgcreate creates a volume group
vgextend adds the rest of the volumes to the volume group
lvcreate creates 4 volumes, 8 gb each, striped over 16 physical volumes
mkfs puts a file system on the volume
mount mounts the logical volumes

If you need to move the LVM structure to another system, then put the new volumes in the appropriate zipl.conf or parmfile. After IPL, run vgscan. vgscan will show which volume groups are available, but they may not be active. To activate them, issue "vgchange -a y vgname".

Disclaimer: This may not be the optimal configuration for your installation and the scripts need to be manually modified to get the results you may want. No warranty is given or implied.

Sample Bash Scripts

vgscan

#!/bin/bash
# 1-vgscan
# setup up LVM and scan for existing configurations
vgscan

pvcreate

#!/bin/bash
# 2-pvcreate - the files system names must be changed to coincide with the 
# volumes mounted by your system
pvcreate -v /dev/dasdx1
pvcreate -v /dev/dasdy1
pvcreate -v /dev/dasdz1
pvcreate -v /dev/dasdaa1
pvcreate -v /dev/dasdab1
pvcreate -v /dev/dasdac1
pvcreate -v /dev/dasdad1
pvcreate -v /dev/dasdae1
pvcreate -v /dev/dasdaf1
pvcreate -v /dev/dasdag1
pvcreate -v /dev/dasdah1
pvcreate -v /dev/dasdai1
pvcreate -v /dev/dasdaj1
pvcreate -v /dev/dasdak1
pvcreate -v /dev/dasdal1
pvcreate -v /dev/dasdam1

vgcreate

#!/bin/bash
# 3-vgcreate
# this script builds a volume group with a single physical volume. Additonal
# volumes are added by 4-vgextend
#
vgchange -a n vgname
vgremove vgname
vgcreate -s 256k -v vgname /dev/dasdx1
#
# the -s parameter (PE size) determines the maximum logical volume size
# so the maximum logical volume size is 65,536 x PE size
# The logical volume has a maximum size of 65,536 Physical Elements (PE's),
# (64K PE size x 65,536 = 4 GB)
#  PE	Maximum
#  size	logical Vol
#  	size 
#  512M	32,768 GB	absolute max
#  32M	2,048 GB	linux 2.4.7 kernel limit
#  4M	256 GB
#  1M	64 GB
#  512K	32 GB
#  256K	16 GB
#  128K	8 GB
#  64K	4 GB
#  32K 	2 GB
#  16K	1 GB
#  8K	512 MB

vgextend

#!/bin/bash
# 4-vgextend
vgextend vgname /dev/dasdx1
vgextend vgname /dev/dasdy1
vgextend vgname /dev/dasdz1
vgextend vgname /dev/dasdaa1
vgextend vgname /dev/dasdab1
vgextend vgname /dev/dasdac1
vgextend vgname /dev/dasdad1
vgextend vgname /dev/dasdae1
vgextend vgname /dev/dasdaf1
vgextend vgname /dev/dasdag1
vgextend vgname /dev/dasdah1
vgextend vgname /dev/dasdai1
vgextend vgname /dev/dasdaj1
vgextend vgname /dev/dasdak1
vgextend vgname /dev/dasdal1
vgextend vgname /dev/dasdam1

lvcreate

#!/bin/bash
# 5-lvcreate
# create 4 logical volumes
# -i 16 - 16 stripes
# -I 16 - 16K per stripe
# -L 8g - 8 gb logical volumes
# - n   - logical volumes name (if -n is omitted, names would be lvol1 to 4)
lvcreate -i 16 -I 16 -L 8g -v vgname -n lvol1
lvcreate -i 16 -I 16 -L 8g -v vgname -n lvol2
lvcreate -i 16 -I 16 -L 8g -v vgname -n lvol3
lvcreate -i 16 -I 16 -L 8g -v vgname -n lvol4

mkfs

#!/bin/bash
# 6-mkfs
mke2fs -b 4096 /dev/vgname/lvol1
mke2fs -b 4096 /dev/vgname/lvol2
mke2fs -b 4096 /dev/vgname/lvol3
mke2fs -b 4096 /dev/vgname/lvol4

mount

#!/bin/bash
# 7-mount
mkdir -p /mnt/lvmvol1
mkdir -p /mnt/lvmvol2
mkdir -p /mnt/lvmvol3
mkdir -p /mnt/lvmvol4
e2fsck -p /dev/vgname/lvol1
e2fsck -p /dev/vgname/lvol2
e2fsck -p /dev/vgname/lvol3
e2fsck -p /dev/vgname/lvol4
mount /dev/vgname/lvol1 /mnt/lvmvol1
mount /dev/vgname/lvol2 /mnt/lvmvol2
mount /dev/vgname/lvol3 /mnt/lvmvol3
mount /dev/vgname/lvol4 /mnt/lvmvol4

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