Partial restore of a make_tape_recovery tape

[Olivier ROBERT]

Dear forum readers,

With Ignite-UX, it is now possible to backup non-root VGs on a system recovery tape, even if they don't contain /usr.

But now, suppose I have two VGs, "vg01" and "datavg". Suppose that the disc which contains "vg00" fails, and I replace the disc, but the disc containing "datavg" is still intact (let's assume the VGs are single disc VGs): is it possible to restore "vg00" only? Even worse, suppose that the disc containing "datavg" fails... Is it possible to restore "datavg" only on a new disc, leaving "vg00" untouched? In both cases, I suppose that "datavg" has not been reorganised at the LVM level (neither extended, nor reduced) since the last make_tape_recovery, neither have been its logical volumes.

Thanks for your help!

Olivier ROBERT

[Pete Randall]

This is why Ignite should really be used only for your root volume group. There other, more appropriate backup methods for your data. Once you reload vg00, you can do a vgimport on your other volume groups, if they're intact. If not, then you need to restore them separately.

This can be done off the ignite tape you described (it's just a tar archive, after all), it's just not the suggested approach - for a number of very good reasons.


Pete

[S.K. Chan]

This thread had a good discussion on non-root vg in make_tape_recovery situation. Patrick explained it very well on the usage of make_tape_recovery for non-root vg. A good practice that we have been doing is to use sysinfo collection tool to save our LVM configuration information for disaster recovery purpose.
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x4f128f960573d611abdb0090277a778c,00.html

[Olivier ROBERT]

Thanks Pete, that's what I feared eventually... I know about the other good methods, but had your answer been positive, that would have been easier to document, having a unique interface for restoring everything!

Btw, I didn't realise one drawback of make_tape_recovery before now: since it's a tar archive, hard links are not preserved...

Thanks!

Olivier

[Michael Duthie]

I always recommend customers to use make_tape_recovery to image the root vg only. Notice I said image not backup. There are far better tools that can be used to backup data. IUX is a installation tool not backup.

We also get customers to run a data collection script (sysinfo, BCS_config, LVMCollect etc)and write the output to a file in VG00 before running make_tape_recovery. Always useful in recovery.

[Olivier ROBERT]

Thanks SK, I will ponder on that... It's strange that nobody told the author of that thread that LVM configuration is stored somewhere in /etc, hence on the root VG!

Regards,

Olivier

[Olivier ROBERT]

Thanks Mike, and yes, I know about better tools... But what are those tools to save LVM configuration? I don't see what more I could get once I have run vgcfgbackup and have the logical volume names...

Regards,

Olivier

[Michael Duthie]

Olivier,

Sorry if I misled you. The data collection scripts are just that data collection, a list of bdfs, lvdisplays. vgdisplay, lanscan etc. Information useful during DR.

You can get sysinfo @ http://hpux.cs.utah.edu/hppd/hpux/Sysadmin/sysinfo-3.3.1/

We (HP Business Continuity Services) use BCS_config which does the same as sysinfo but we have developed a sister script which rebuilds & mounts the lvols on differing hardware from the BCS_config output.

www.hp.com/go/recovery

[Olivier ROBERT]

No problem Mike, and thanks for the information!

Olivier

[Frank Slootweg]

> Btw, I didn't realise one drawback of make_tape_recovery before now:
> since it's a tar archive, hard links are not preserved...

I am by no means a specialist in Ignite-UX, but tar(1) (and pax(1) which is used by Ignite-UX) *can* preserve hard (file) links. Perhaps others can comment on whether or not Ignite-UX preserves hard links. I assume so, otherwise for example device files, man pages, many commands, etc. would be a mess.

[Olivier ROBERT]

Hi Frank,

I didn't notice that feature of tar, which is not available on all tar commands, but that could turn useful. I'm going to try this as soon as I get back to work. Thanks for the information!

Olivier