Friday, August 31, 2018

Expand AIX disk using chvg

How to expand volume group space without extending new disk to volume group?? So this post is helpful for AIX setup where addition of new disk is time consuming, so instead of adding new disk it will always good option to expand disk from storage end and then expand volume group on AIX level using chvg –g command.Consider situation where there is no free PP available on volume group and AIX admin want to immediately add additional free PP to volume group

There are 2 option to add space to AIX volume group,
1. Add new disk to volume group.
2.Expand existing disk size in volume group.
If situation demand immediate space addition to volume group then 2nd option is the best option.

Which details storage admin need to expand existing disk on AIX ??
Storage admin need Lun Id and Lun name for expanding disk from storage end.

Storage specific command to find Lun details.

EMC storage disk – powermt display dev=hdiskpowerX
IBMstorage - mpio_get_config –Av |grep hdiskX
XIV storage - xiv_devlist |grep hdiskx
Also admin can use lspv –u command to see PV details.
There may be different type of storage, so use command according to storage type to identify Lun ID details

After finding Lun id by AIX admin, provide the same to storage admin and ask to expand same disk with required size. Next step is, execute chvg –g vgname by AIX admin on server. confirm volume group expansion by command 
#lsvg vgname

What if chvg –g vgname command not expanding current disk space ??
 Answer to this question is, admin need to varyoffvg vg and then vary on vg. Here need downtime, because while varyoff VG admin first need to umount corresponding filesystem.

How to handle following error message ??
"chvg -g not supported in the rootvg"
0516-1380 chvg: Re-sizing of the disks is not supported for the rootvg.
0516-732 chvg: Unable to change volume group rootvg.
This error mesage will appear on AIX 5.3 and AIX 6.1 TL lower than 03.

chvg -g rootvg  command supported version are like below.
AIX V6.1 TL3 and higher (6100-03-00) resizing rootvg disks is now supported. on lower version this command will not work for AIX rootvg volume group.

Next query is how AIX admin expand volume group disk on AIX HACMP environment??
Step 1: First provide Lun details to storage team.
Step 2:/usr/es/sbin/cluster/sbin/cl_chvg -g datavg.
Step 3: Observer whether volume size is by using command 
#lsvg vgname


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