Procedure for swapping out the Root Volume disks.

[Khalil Ahmed]

We would like to replace mirrored internal 18 Gbyte disks with mirrored internal 36 Gbyte disks in our N-Class machine. These disks house the root volume and hence the HP-UX O/S, the application and its associated database reside on external EMC disks. Can anyone suggest the best procedure for swapping out these disks and still be able to boot up the machine? One option is to use Ignite except someone has mentioned that the Ignite approach my fail because of the disks being a different size, is this correct? Another option is to re-load the HP-UX O/S onto the new 36Gbyte disks and then use vgimport to re-import the volume groups (this would involve quite a bit a of work as we have a number of VGs and quite a few EMC disks assigned to the VGs). If there are any good suggestions put forward please provide as much detail of the procedure as possible.

Kind Regards

Khalil Ahmed
SAP/Oracle Team Leader

[George Petrides_1 · Accepted solution]

Khalil,
Ignite-UX will do the job and will work with bigger disk since it will do the pvcreates on the new disk and continue. You will need to interact with a menu since it's a different disk but that's about it. What will NOT work in your case is COPYUTIL that makes a bit by bit copy of the disk. You could mirror to the 36GB disk and then umirror the 18GB disks and replace but it is a very complex procedure and you might have a lot of problems. Also, adding the 36GB disks to the existing vg00 might cause problems with the maximum Physical Extends per disk since you have already 18GB disks in the group. Your best bet is Ignite-UX that is a safe procedure, and if something goes wrong you can still go back to your 18GB drives and keep working.
Hope this helps,
George

[Tom Geudens]

Hi,
Ignite should/will work ... I don't know of any reason why it shouldn't. These forums are full of posts where the root disk is "extended" with Ignite.

I believe (check this !) you will "loose" the mirror though (and you'll have to recreate that afterwards).

Regards,
Tom

[Kenneth_19]

You might need to create a bootable mirror on the new disks with the existing ones:

# Create alternate boot disk and reserve boot area
pvcreate -B /dev/rdsk/c?t?d? (the new 36Gb disk)
# Make disk bootable
mkboot /dev/dsk/c?t?d?
# mkboot -a "hpux (;0)/stand/vmunix" /dev/dsk/c?t?d?
# verify the existence and contents of the LIF
lifls /dev/dsk/c?t?d?
# Extend root disk vg with the new disk
vgextend vg00 /dev/dsk/c?t?d?
# Mirror the root disk LV by LV with the following sequence, notice the "-m 2" indicates that this is the second mirror copy in addition to your existing mirror
lvextend -m 2 /dev/vg00/lvol1 c?t?d?
lvextend -m 2 /dev/vg00/lvol3 c?t?d?
lvextend -m 2 /dev/vg00/lvol2 c?t?d?
lvextend -m 2 /dev/vg00/lvol4 c?t?d?
lvextend -m 2 /dev/vg00/lvol5 c?t?d?
lvextend -m 2 /dev/vg00/lvol6 c?t?d?
lvextend -m 2 /dev/vg00/lvol7 c?t?d?
lvextend -m 2 /dev/vg00/lvol8 c?t?d?

You can now try to restart the server and boot it up with the new root disk and verify if everything works fine, you can afterwards remove the old 18Gb disks after lvreduce the old mirror.

Regards,
Kenneth

[Stefan Farrelly]

Youre going to have a big problem in that the volume group limit of max PE per PV is probably not big enough to copy with 36Gb disks which means you will have to create a new volume group (new boot disk). The best tool to do this by far is IGNITE. It will make a bootable DDS backup of your current vg00, you then replace both your 18GB drives with your new 36Gb drives then boot off the Ignite tape, and this will easily reload your current vg00 config onto the new 36Gb drives. Its really easy.

All you may have to do afterwards is re-import your non vg00 volume groups (which you could easily get around by restoring all /dev/vgXX dirs except vg00 after the ignite tape is done [back these up separately first] then simply activating your non vg00 volume groups).

[Joaquin Gil de Vergara]

Is complex but secure if you do it carefully
(First of all make a toal backup and a Ignite tape!)
break the mirror of the root volume group

# for i in /dev/vg00/lvol*
>do
>lvreduce $i /dev/dsk/disk_b
>done

Replace the disk_b for the new
# vgreduce vg00 /dev/dsk/disk_b
# ioscan -fn
# pvcreate -B /dev/rdsk/disk_b
# mkboot /dev/rdsk/disk_b
# vgextend vg00 /dev/dsk/disk_b
Remember mirror the LIF area!
# for i in $(lifls /Dev/dsk/disk_a)
> do
> lifcp /dev/rdsk/diska:$i /dev/rdsk/disk_b:$i
> done

If you want to extend any LV extend make it over the disk_A

# lvextend -L /dev/vg00/lvolx /dev/dsk/disk_a

If you want to extend the swap space make this

# /sbin/lvchange -s n /dev/vg00/lvol2

Extend it over disk_a
# lvextend -L /dev/vg00/lvol2 /dev/dsk/disk_a


Now create the mirror over the disk_b (all LV will be contiguos over it!!)

# for i in /dev/vg00/lvol*
> do
> lvextend -m 1 $i /dev/dsk/disk_b
> done

Break the mirror over disk_a replace it and make the mirror again

# for i in /dev/vg00/lvol*
> do
> lvreduce -m 1 $i /dev/dsk/disk_a
> done

Replace the disk_a and recreate the mirror

# vgreduce vg00 /dev/dsk/disk_a
# ioscan -fn
# pvcreate -B /dev/rdsk/disk_a
# mkboot /dev/rdsk/disk_a
# vgextend vg00 /dev/dsk/disk_a
Remember mirror the LIF area!
# for i in $(lifls /Dev/dsk/disk_b)
> do
> lifcp /dev/rdsk/disk_b:$i /dev/rdsk/disk_a:$i
> done

# for i in /dev/vg00/lvol*
> do
> lvextend -m 1 $i /dev/dsk/disk_a
> done

All LV all noew contiguos over the new disks

Reassign the strict policy to the swap!

# /sbin/lvchange -s y /dev/vg00/lvol2


NOTE: If you want to change the size of / use a Ignite tape (but probably you don`t need) ;-)

[T G Manikandan]

check this attachment.

Might be useful