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How to break a root mirror

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Frequent Advisor

How to break a root mirror

Hello Guru's

What is the procedure to break root mirror in HP-UX. Before doing the patching we are thinking of breaking mirror, so that after the patching if the OS on primary corrupts, we should be in a position to recover/boot the server from secondary disk. Please advise.
Esteemed Contributor

Re: How to break a root mirror


you can split your LV by using #lvsplit command.

So for example:

#lvsplit /dev/vg00/lvol1

It depends on what files the patch fixes, you can specify all the LVOL's from your VG00 on the same command line:

#lvsplit /dev/vg00/lvol1 /dev/vg00/lvol2 /dev/vg00/lvol3 ...

then look at command #lvmerge , which is used to synchronize the LVOL's.
Acclaimed Contributor

Re: How to break a root mirror

If running 11.23 or 11.31, just use DRD to clone the OS to another disk, install the patches to the clone.

Then boot the server from the clone.

In case of problems, just boot from the original disk.

You can do all this with minimum downtime (1 reboot only, if all works).

Hope this helps!

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P Arumugavel
Respected Contributor

Re: How to break a root mirror

Frequent Advisor

Re: How to break a root mirror

Thanks for your replies,

If I do a lvsplit initially and during patching my primary disk got corrupted, what is the procedure to recover it from the backup lv or lv's
Esteemed Contributor

Re: How to break a root mirror

I recommend splitting all of the LVOL's of your vg00 and then if your primary disk becomes unbootable, then boot with your secondary disk (the one that was just splitted) and 'lvmerge' the volume back. But be carefull to use the lvmerge command in the right direction! ! !
Esteemed Contributor

Re: How to break a root mirror

Quicker / more straightforward method would be using DRD, as was suggested in previous posts.
Frequent Advisor

Re: How to break a root mirror

Hi Jayraj,

Scenario 1 ( No mirrored Disk)

Before go for patching take ignite backup of your system as recommended by hp.

If you dont have an option to take ignite in tape, configure ignite server and take ignite backup..

Take kernel backup.

Reboot the server and ensure server comes up prior to patching.

Check for error message's, service status, dmesg, /var/adm/syslog/syslog.log.

Then go for patching.

Scenario 2 ( Mirrored disk )

split the root disk as suggested.

Reboot the server and ensure both (primary /secodary) disk's are bootable.

Take kernel backup

Then go for patching.


if you face any issue after patching. you have an option to boot in secondary disk merge the primary with secondeary and update the boot informatio.


Uninstall the installed by patches.

If you need to remove the installed patch bundle

1) Generate a list of patches to be removed which were installed as part of this change

# swlist -l product -a install_date | grep 2009MMDD | awk '{print $1}' > /tmp/patches_to_remove.txt

NOTE: In the above line 2009MMDD corresponds to the install date of the patch bundles. For example if
the install date was Jan 17 2009, then 2009MMDD should read 20090117
NOTE: The list of patches to be removed should be verified to confirm that only patches installed as a
result of this change will be removed. Check the /tmp/patches_to_remove.txt file against the list of patches
installed in the /var/adm/sw/swinstall.log and /var/adm/sw/swagent.log files.

2) Remove the patches
# swremove -x mount_all_filesystems=false -x autoreboot=true -f /tmp/patches_to_remove.txt

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