topic Re: SAN disk / volume group expansion in Operating System - HP-UX

SAN disk / volume group expansion

Mike Smith_33 — Wed, 08 Feb 2006 15:22:08 GMT

I have a volume group, vg04, that was 6gb in size. I wanted to increase the size to 11gb. The volume group is really a SAN lun so I went into the SAN and increased the size of the lun to 11gb. The problem now is how to increase it on HP 11.11. From OpenVMS it is real simple to do.

I have looked through some postings but they mostly seem to deal with increasing the lvol not the vg device. Some talked about adding physical disks into a volume group which is sort of what I did but not exactly.

The vg04 device had one lvol when it was 6b and that was a 6gb lvol. I would like to expand vg04 to 11 gb and add a 5gb lvol to vg04 and leave the existing 6gb lvol intact.

Any help is appreciated.

Re: SAN disk / volume group expansion

A. Clay Stephenson — Wed, 08 Feb 2006 15:26:39 GMT

That's not gonna work. You could have added an additional 5GB LUN to the VG and that would have worked just fine. Even if the OS recogized that the LUN is now larger, the LVM data structures written when the VG was created limit the maximum number of extents to those of the largest PV in the VG --- unless you actually specified the max pe's when you created the VG.

Re: SAN disk / volume group expansion

DCE — Wed, 08 Feb 2006 15:27:49 GMT

pvcreate the new 5 GB lun

vgextend /dev/vg04 /dev/dsk/cxdydz

lvcreate the new lvol

you can direct the new lvol onto the new lun

see man on
pvcreate
vgextend
lvcreate
lvextend

Re: SAN disk / volume group expansion

TwoProc — Wed, 08 Feb 2006 15:28:05 GMT

Mike,

The system already "knows" the size of the lun, so it's not going to get it for you.
It would have been better to create another lun, and just add it as a pv to the volume group.

To have your new disk recognized in the manner in which you did it, you'd have to remove it from the vg(and the whole vg if it is the only pv in it), then remove the pv (pvremove).

Then, go back and pvcreate it, then vgcreate (or vgextend) with it.

Of course, all of the above will wipe out everything on the disk, so make sure you have a backup.

Re: SAN disk / volume group expansion

Mike Smith_33 — Wed, 08 Feb 2006 15:33:02 GMT

HP-UX is a bit different, no problem, I will learn someday. With OpenVMS I could have dismounted and privately mounted then extended the disk size.

DCE, I don't have another lun, it is the same one only increased in size from my EVA.

It seems a bit of a waste of what the EVA gives you to have to create additional luns when the EVA allows easy expansion.

Re: SAN disk / volume group expansion

Sundar_7 — Wed, 08 Feb 2006 15:35:21 GMT

Mike,

Call HP response center if you have a support agreement and ask for "vgmodify" . This is an unsupported tool that you can use to increase the MAXPE of the volume group so that it will recognize the new bigger LUN.

Sundar.