topic Re: Boot Mirror Synchronization in Operating System - HP-UX

Boot Mirror Synchronization

Manuel Urena — Mon, 03 Aug 2009 14:35:12 GMT

Hi all,

I've encountered an interesting scenario while doing some experimentation on a Test System.

The system is an RP7400 and this is the sequence of events:

- The system has two internal mirrored boot disks in vg00.
- I shut the system down took out the primary boot disk and replaced it with a new drive.
- Powered the system back on and because the primary boot disk is a new drive the system booted off the alternate bootpath.
- I proceeded to resynchronize vg00 (vgcfgrestore, mkboot the new drive... etc..)
- Then to test if everything was fine I rebooted the system again, now the system booted off the primary boot disk (which had the new resynchronized disk).
- Then I shut the system down again and then I replaced the new drive (primary boot disk) with the old drive I took out at the very beginning.

I noticed the system booting off the old drive without too much issues (The system printed "Resynchronized volume group /dev/vg00" during boot time) and there doesn't seem to be any stale PEs at the moment. But I kept receiving VXFS errors on the syslog.

What is the strategy that Mirror/UX uses to resynchronize disks in this case? Which drive is used as the master copy?

I am afraid that now that the spare drive has boot files and a BDRA it may cause issues if I use it as a replacement in a production system.

Thanks for your help,

Manuel

Re: Boot Mirror Synchronization

SoorajCleris — Mon, 03 Aug 2009 14:44:41 GMT

Hi,

The mirror /UX never synchronise the disks. It will synchronise the LV.

PVRA is never synchronised.

Regards,
Sooraj

Re: Boot Mirror Synchronization

SoorajCleris — Mon, 03 Aug 2009 14:46:45 GMT

Hi,

There are mirror consistancy and recovery policies for this. And again you may try to run vgsynch and lvsynch manually also.

Regards,
Sooraj

Re: Boot Mirror Synchronization

Manuel Urena — Mon, 03 Aug 2009 14:52:51 GMT

Thanks for your answers. My question doesn't have to do with BDRA resynchronization, I know LVs are the objects getting in synch.

My question has to do with what drive in this situation becomes the master copy for synchronizing the LVs using the default mirror policies?

Does the primary boot disk always become the master in a two-way boot mirror regardless like in this case it contains a slightly old representation of the data?

Thanks.

Manuel

Re: Boot Mirror Synchronization

SoorajCleris — Mon, 03 Aug 2009 14:57:01 GMT

Hi,

For finding out why the system booted from the alternate boot path first time, you may check the syslog ,dmesg.But unfortunatly I think you have restarted the system too many times so I dont think your OLD syslog will be there.

Still as it booted again from the same disk, that disk may be giving intermitted problem.

Regards,
Sooraj

Re: Boot Mirror Synchronization

Andrew Rutter — Tue, 04 Aug 2009 21:22:57 GMT

hi,

from my understanding the disk booted is the 'master' as you call it. this then updates the alt disk

what you have done would not normally be done, but you have probably updated the old alt with info from the old primary disk.

effectively going backwards?

Andy