LV SPLIT

rooble — Thu, 05 May 2011 02:42:40 GMT

Dear Experts,

I patched one box (11iv2). As per instrunction Before patching I splitted all lvols of vg00. unfortunatly after patching system was not coming up. could you please let me know wht to do to bring the box up?

Regards,

Rob

Re: LV SPLIT

g3jza — Thu, 05 May 2011 04:31:55 GMT

Hi,
assuming that you are using mirroring and all the mirrored LVOL's reside on different disk than the one you booted from, then why not trying to boot from your alternate mirrored (splitted) disk?

Re: LV SPLIT

Shibin_2 — Thu, 05 May 2011 06:08:00 GMT

what is the error it shows?

Re: LV SPLIT

Torsten. — Thu, 05 May 2011 06:13:50 GMT

You probably need to boot into "-lm" mode and vgexport/vgimport the VG in order to make the "backup" disk a new standalone VG.

The current LVM admin guide has all the steps (page 89 - Splitting a Volume Group)

document title is

HP-UX System Administrator's Guide:
Logical Volume Management
HP-UX 11i Version 3

Re: LV SPLIT

rooble — Thu, 05 May 2011 08:37:57 GMT

thanks all,

I got the procedure from HP Guy.
lets say /dev/dsk/c0t1d0(pri) and /dev/dsk/c0t2d0(sec) PV's are part of VG vg00. Now the requirement is that we upgrade from the first disk and something goes wrong, boot from the second. In my method, we cannot boot from the second per say, but I strongly believe that it can atleast help in restoration.

1) Split all the mirrored LV's in vg00.

lvsplit /dev/vg00/lvol1
lvsplit /dev/vg00/lvol2
lvsplit /dev/vg00/lvol3
lvsplit /dev/vg00/lvol4
lvsplit /dev/vg00/lvol5
lvsplit /dev/vg00/lvol6
lvsplit /dev/vg00/lvol7
lvsplit /dev/vg00/lvol8

after the slipt you will find these devices in /dev/vg00 directory.

lvsplit /dev/vg00/lvol1b
lvsplit /dev/vg00/lvol2b
lvsplit /dev/vg00/lvol3b
lvsplit /dev/vg00/lvol4b
lvsplit /dev/vg00/lvol5b
lvsplit /dev/vg00/lvol6b
lvsplit /dev/vg00/lvol7b
lvsplit /dev/vg00/lvol8b

2) Upgrade the OS now. Meaning it would affect the data only in the first disk(pri).

3) DECIDER :

a) If the upgrade succeeds, that is you are successful in booting through the pri disk, and you find all is find, just remove the second set of LV's

lvremove /dev/vg00/lvol1b
perform the same for other LV's aswell.

Now remirror the boot disk as prescribed by HP docs.

b) If the kernel refuses to boot from the pri. Boot with "/stand/vmunix.prev" to lvm maintenace mode.

at ISL prompt ...issue..

ISL>hpux -lm vmunix.prev

Once you are into the LVM maintenence mode..issue the following commands....

vgchange -a y vg00
lvmerge /dev/vg00/lvol1 /dev/vg00/lvol1b

NOTE: The order of LV specification is very important. The first LV is destination and the second is source. There by I overwrite the data on the lvol1 with the data that was orginally preserved in lvol1b. Now you repeat the procedure for the rest of LV's in vg00.

vgchange -a n vg00
reboot

4) Now you can boot again normally from primary boot disk. Once booted verify whether the version of HPUX is the previous one by issuing "uname -a".

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