topic Re: Replacing system disks in Operating System - HP-UX

Replacing system disks

Nappy_1 — Thu, 29 Nov 2007 10:30:28 GMT

we have a rp8400 server with 4 disk slots.
vg00 is running on 2 36 GB disks.
we want to replace those disks with 2 72GB disks without an ignite backup/restore.

is it possible to plug new disks with older disks, then include them in the vg00 and remove 36GB disks?
if yes, please provide me a detailed procedure

Re: Replacing system disks

A. Clay Stephenson — Thu, 29 Nov 2007 10:35:39 GMT

Probably not; if you are running 11.11 then almost certainly not. When a VG is first created, the number of physical extents is sized to accomodate the largest disk listed in the vgcreate command UNLESS you explicitly override the defaults. Once set, tghe number of PE's cannot be increased so while your 72GiB disks could be used, you would only be able to use the first 36GiB on the disk. At 11.23 and up there is a vgmodigy command which can be used to icrease the number of PE's per PV.

Re: Replacing system disks

A. Clay Stephenson — Thu, 29 Nov 2007 10:36:23 GMT

... Ooops, that should be "vgmodify".

Re: Replacing system disks

Luk Vandenbussche — Thu, 29 Nov 2007 10:36:52 GMT

It depends on the setting off your vg00

Check this settings of your vg (vgdisplay -v vg00)

Max PE per PV 4350
VGDA 2
PE Size (Mbytes) 4

In my case : 4350 x 4 = 17400
So I can max use a 18 GB disk in vg00

If this value is in your case 35000 then you can not add disks with a bigger capacity then 36 GB in your vg00 and the only solution is working with Ignite/UX

Re: Replacing system disks

Victor BERRIDGE — Thu, 29 Nov 2007 10:37:22 GMT

Greetings,

It will depend of :
1) Do you have mirrorux?

2)Max PE per PV

2)If default value then the answer will be no...
(because you could not the full size of the new disk so not much of use...

All the best
Victor

Re: Replacing system disks

Tim Nelson — Thu, 29 Nov 2007 10:43:44 GMT

Ignite is your best bet and the safest.

All your options will require downtime.

Depending on your currently layout if 36GB disk two is a mirror you can reduce it, remove it, insert the 72GB drive, then follow the mirroring procedures. Repeat for the other drive.

The first issue you will run into is that the max_pe for vg00 is probably too small for the 72GB disk. If you have a patched 11.23 or 11.31 you can use the vgmodify commands in maintenance mode to increase. There is an HP doc for Dynamic lun expansion for this.

You could put the new disk in a new VG and use dd but you will have to do more maintenance mode changes to remove vg00 and change the name of vgnew to vg00. Good luck here.

I still think your best bet is to create an Ignite image, restore it to the 72GB drive, boot it, check it, you can always boot back to the 36GB disk if there are any issues.

Re: Replacing system disks

Nappy_1 — Fri, 30 Nov 2007 11:27:56 GMT

Thanks Guys