Creating Normal,Big,Scalable VG on AIX

 
 
 

Tuesday, 17 July 2012

 

Creating Normal,Big,Scalable VG on AIX

After SAN team assigned Disks/LUNs to the server,we need to scan it from OS side and once scanned completed successfully and disks are available we will be able to create Volume Group , Logical Volume and File Systems.
Remeber :
Volume Groups have 3 different types:
Regular – Limit of 128 Physical Volumes per VG, and 256 Logical Volumes per VG
Big Format – Limit of 256 Physical Volumes per VG, and 512 Logical Volumes per VG
Scalable Format – only for AIX 5.3 and above, PV and LV limitations can be defined by the administrator
To read more about AIX Volume Group Click Volume Group In AIX . Here I have taken example of creating a VG named sapvg . The creation procedure of paging space or log lv we will cover in another tutorial.

Procedure for creating filesystem :

1. Run cfgmgr to rescan the harware for OS. If any new Luns are presented to the system it will detect . On our example these Luns are hdisk2 , hdisk3 and hdisk4
cfgmgr
As you can see below Luns hdisk2 , hdisk3 and hdisk4 are free ( None)
$ lspv
hdisk0 00083535e5c25171 None
hdisk1 00083535457a51d6 rootvg active
hdisk2 00083535f98c392b None
hdisk3 0008353512aa7bd8 None
hdisk4 000835357cb3824b None
2.creates Normal vg with 128MB PP size
mkvg -y sapvg -s 128 hdisk2 hdisk3

OR

creates vg with default PP size
mkvg -y sapvg hdisk2 hdisk3
To Create Big volume group
mkvg –B –y [VG Name] -s [PP Size] [PV Name]
The –B flag creates a “big” volume group. A regular format VG has an LV limit of 256. The big VG format has a limit of 512.
Similarly to Create Scalable volume group
mkvg –S –y [VG Name] -s [PP Size] [PV Name]
3 .Verify it
lsvg -p sapvg;
lsvg sapvg
4.Creating an enhanced (JFS2) LV saplv on sapvg Volume group with 32 GB space
mklv -y saplv -t jfs2 sapvg 32G

Or

Creating an enhanced (JFS2) LV saplv on sapvg Volume group with 32 GB space on hisk2
mklv -y saplv -t jfs2 -a e sapvg 32G hdisk2
5.Creates fs with specified saplv and set auto mount
crfs -v jfs2 -a -d /dev/saplv -m /sap
6.Mount the filesystem
mount /sap
7.Set owner/permission as required
chown -R sapuser:dba /sap

Extending a VG

1. In our case we have one disk left unassigned hdisk4 . Let’s use it to extend sapvg VG
extendvg sapvg hdisk4
2. Verify it
lsvg -p sapvg

Reducing a VG

reducevg -f sapvg hdisk3

Increasing/Reduceing a filesystem

1) Check the available space in the VG . Read more about lsvg command click lsvg VGName: Explanation of the Volume Group Characteristics
lsvg sapvg
2) If space is there increase it.
chfs -a size=+30G /sap
3. Reducing filesystem size is only possible for JFS2 not with JFS . Read more about filesystem click  JFS Vs JFS2
chfs -a size=-30G /sap

Removing a filesystem

1. Un mount it .
umount /sap
2. Remove the filesystem with rmfs and it will automatically remove the corresponding LV also.
rmfs /sap

Removing only LV

rmlv /dev/saplv

####
umount /filesystem
varyoffvg testvg
exportvg testvg
lspv

rmdev -dl hdiskXX

cfgmgr
lspv
importvg -y testvg hdiskXX
varyonvg testvg
mount /filesystem

mkvg -S -y testvg -s 256 hdiskXX
mklv -y lv_test -t jfs2 -L lv_test testvg 10240M
crfs -v jfs2 -m /pure -d lv_test -g testvg -A yes -p rw -a logname=INLINE

mount /filesystem
chmod 755 /filesystem
####

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