topic Re: Stop and re-sync mirror in Operating System - HP-UX

Stop and re-sync mirror

Fernando Boza — Thu, 29 Jan 2009 22:01:43 GMT

I have a server with HP-UX 11.11 atached to two storages. I have mirror-ux within storages.

I need shutdown one storage for maintenance and then go on again.

What is the most easy method for stop and resync the mirror?

Re: Stop and re-sync mirror

Robert-Jan Goossens — Thu, 29 Jan 2009 23:17:16 GMT

Hi Fernando,

Have a look at this white paper and check if you have next patches installed.

For 11.11: Patches PHKL_31216 and PHCO_30698 (or superseding patches)

http://docs.hp.com/en/7161/LVM_OLR_whitepaper.pdf

Regards,
Robert-Jan

Re: Stop and re-sync mirror

Steven E. Protter — Fri, 30 Jan 2009 00:30:00 GMT

Shalom

lvextend -m 0

to break it

lvextend -m 1

to rebuild
rebuild will take some time.

SEP

Re: Stop and re-sync mirror

sujit kumar singh — Fri, 30 Jan 2009 07:17:18 GMT

Hi Fernando,

As a word of caution before doing this i shall suggest you to run the following commands so that you can have the PV list for the existing VG as well as the a map file in place for the VG(s).

for all the VGs that are having the mirrors (MirrorDisk/UX)on both the storages as said by you Ealier, PLease run.

#vgexport -p -v -s -m /tmp/.Before_activity.map /dev/

#vgexport -p -v -f /tmp/.Before_Activity.PV_list //dev/

Kepping these map files and the PV list for the involved VGs shall be good.

Regards
Sujit

Re: Stop and re-sync mirror

Torsten. — Fri, 30 Jan 2009 08:07:50 GMT

You can simple stop disk access on lvm level with "pvchange -a n ...", see

man pvchange

Example:

pvchange -a n /dev/dsk/c3t0d0s2
Warning: Detaching a physical volume reduces the availability of data
within the logical volumes residing on that disk.
Prior to detaching a physical volume or the last available path to it,
verify that there are alternate copies of the data
available on other disks in the volume group.
If necessary, use pvchange(1M) to reverse this operation.
Physical volume "/dev/dsk/c3t0d0s2" has been successfully changed.

Re: Stop and re-sync mirror

OldSchool — Fri, 30 Jan 2009 15:33:14 GMT

I may be grossly oversimplifying this, but would not "lvsplit / lvmerge" work for this.

I'm unclear as to whether the original poster was attempting to move data off one storage system to another prior to maint. or if he simply needed to break off the mirrors.....

Re: Stop and re-sync mirror

Armin Kunaschik — Fri, 30 Jan 2009 17:11:28 GMT

The most easy way is simply do nothing.

In most cases the system will notice that the missing storage is back and start syncing in background.
In all other cases, when the system does not recognize the storage, simply do ioscan and vgsync for any vg with stale extents (or lvsync respectively).

This biggest advantage here is, that you won't need to resync all extents, but only those that changed while the mirror was down.

If, for some unkown reason, none of the mentioned steps work to bring the mirror back online, you're still free to break the mirror, even if the mirror disks are completely gone.

My 2 cents,
Armin

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