topic Re: Root disk mirror in Operating System - HP-UX

Root disk mirror

surya_3 — Wed, 26 Feb 2003 08:56:16 GMT

Hi all,

I wish to upgrade my hp11.00 server to 11.11 .The root VG of the server is mirrored . My plan is to split the mirror and use one disk for installing 11.11 , once every thing is fine i will do mirroring again ..
The above server is the Cell Manger of Omni back too. PLease suggest the steps to follow for a successful installation

Thanks,
SPV

Re: Root disk mirror

monasingh_1 — Wed, 26 Feb 2003 09:29:59 GMT

I think the safest way is to stop OB, take the ignite recovery tape and then go ahead with upgrade .

before upgrade , check to see if you can create the kernel successfully.

Also check the OB dependencies if any with the new OS and any specific config changes are required for 11.11.

If upgrade failes, just put the recovery tape in and boot from there , you should be up and running in an hour or two..

Re: Root disk mirror

Rajeev Shukla — Wed, 26 Feb 2003 10:02:49 GMT

Hi SPV,
First take a make_recovery and then split the mirrors using lvreduce and then use vgreduce to remove one disk off the mirror.
Once done reboot the system with the left over root disk to make sure you are safe in using this book disk in case of emergency
Then you can start loading the 11.11 on the other free root disk.

Re: Root disk mirror

eran maor — Wed, 26 Feb 2003 11:12:49 GMT

Hi

there isnt any issue with the mirror that your server is a CELL server of omniback .

do a make_tape_recovery to your system .

boot in lm mode and do :
vgchange -a y -q n /dev/vg00
lvreduce -m 0 /dev/vg00/lvolX /dev/dsk/cXtXdX .

boot from the cd install disk and do the install on the hp-ux 11.11 .

you need to remember that you will need to install all the software that you had on the hp-ux 11.00 .

also save on the side all the config files that you need like :
/etc/passwd
/etc/group
/etc/rc.config.d/netconf
/etc/rc.config.d/nfsconf .

and any config file that is impotent to you .

Re: Root disk mirror

Matthias Gottschalk — Wed, 26 Feb 2003 15:03:28 GMT

Hi SPV,
I guess you want to have the mirror as a sort of backup of your
root volume group. In that case you are still able to fallback if
anything is messed after the upgrade.
I would rather do a lvsplit than reducing the logical volume. In
that case you have the backup on the logical volumes with an
extension 'b'. Afterwards you can perform the upgrade on the
primary disk. If the system is fine afterwards you can merge the
disks again (take care about the syncronisation direction
lvmerge /dev/vg01/lvol1b /dev/vg01/lvol1 will overwrite lvol1b).
The sizes may not change during the upgrade otherwise you
cannot merge without an extend of the old lvol beforehand.
In case of a disaster you can fallback to the old disks (by
using setboot and lvlnboot).

Regards,
Matthias

Re: Root disk mirror

John Dvorchak — Wed, 26 Feb 2003 17:20:53 GMT

I don't quite agree with the other respondents. If you lvreduce and vgreduce the disk I am not sure that you can boot off of it. I would confirm that the boot up is NOT looking for a quorum by checking the AUTO log:

lifcp /dev/dsk/c_t_d_:AUTO -

where that is the disk you want to keep to use as the backup. It should say something like this:

root>lifcp /dev/dsk/c0t5d0:AUTO -
hpux -lq 52.5.0;0)/stand/vmunix

where "hpux -lq" means it is not looking for a quorum and will boot off of that disk. Then shutdown and boot off of the CD and install to the other disk.

Re: Root disk mirror

P.H. Vogt — Thu, 27 Feb 2003 16:03:10 GMT

step 1 verify both disks are bootable or just do

mkboot
mkboot -a "hpux -lq"

for both rootvg disks.

If you get a non boot disk message with mkboot your mirror disk is not bootable.

step 2 make a make_recovery tape If possible use the option -A.

step 3 stop all applications or even better go in single user mode.

step 4 just physically remove 1 disk from the system.

step 5 lvreduce all lv's and do a vgreduce -f vg00

step 6 upgrade to 11i

step 7 install the 11i mirroring software B2491BA and put the disk in the system again

step 8 pvcreate -fB
/dev/rdsk/c#t#d0
vgextend vg00

for f in `find /dev/vg00 - type b`
do
lvextend -m 1 $f
done

mkboot
mkboot -a "hpux -lq"

I just did such upgrade. It went without any problems only the root file system was 15 Mb too small so I had to restore the make_recovery tape first to increase the root file system. I tried some LVM tricks but extending the root file system is not easy. Next time root is too small I shall try a hpux -lm.

Paul

Re: Root disk mirror

IT Response — Sat, 01 Mar 2003 20:42:01 GMT

I've used the exact same splitting of the root mirrors that you're intending to use. The splitting, which is done for roll back purposes and should also include two make_recovery tapes, is the exact same procedure used with lvsplit and lvmerge commands for hot backups in a two mirror environment. With one provision, you have to split vg00/lvol1 through lvol8 from lvm maintenance mode, "...hpux -lm -ls...". This way you can activate and deactivate vg00 as needed. And since most of the commands you'll need are found in /etc you shouldn't have to mount /usr. Here is a short outline:

mkdir /usr_backup /var_backup, etc
reboot
interrupt boot
ISL>hpux -lm -is
lvsplit -s backup /dev/vg00/lvolxx, etc.
fsck /dev/vg00/lvolxxbackup
vgchange -a y vg00
mount /dev/vg00/lvolbackup /usr_backup

Note A: Some people don't mirror lvol2, swap, and this procedure wouldn't apply in this case.

Note B: All rules for boot disks apply but don't invoke lvlnboot, etc., unless rollback is needed.

Note C: Verify you're alternate boot path is pointing at the CDROM instead of the old version of the O/S.

Note D: Make an ignite make_recovery tape immediately after the new O/S install since this now becomes your alternate until re-mirroring.

Some people consider this a lot of work and somewhat obsolete since ignite make_recovery became so easy but I believe this to be an additional safeguard in the event of a problem. When your point of no return occurs and you no longer need the old version of the O/S just pvcreate and follow the mirroring of the boot disk procedure.