Unmirror rootvg for ML/TL updates?

[Mag0007]

Anyone here practice, unmirroring rootvg before applying ML/TL?

I have a NFS share with my ML8, I usually do a mount and an smit update_all

Is this a good practice or overkill?

 

[DukeSSD]

Good question Mag0007.

I unmirror for a mksysb because there can be problems restoring if you don't but I've never had a problem doing a ML, TL or SP upgrade on a mirrored rootvg.

Anyone else care to comment?

 

[zaxxon]

We never unmirror for applying a ML nor for an mksysb. We never did this in the last years and never had any problems because of this.
We only unmirror cause of removing a disk cause for example if it has a defect or if we distribute our disks anew for some layout reason.

laters
zaxxon

 

[DukeSSD]

zaxxon,
have you tried restoring those mksysb's?
mksysb's seem to work fine if the rootvg is mirrored but the restore causes the problem....

 

[Mag0007]

Okay guys, here is what I tried, and works perfectly!

Unmirror my rootvg
Reduce my rootvg (remove hdisk1 from rootvg)
alt_diskinstall -C hdisk1 (this takes a mksysb of hdisk0, and restores it to hdisk1, and change the bootlist to hdisk1, and sets bootimage on hdisk1)
Reboot (will automatically boot to hdisk1)
Apply TL

Just tried, it works awesome!

 

[Mag0007]

Sorry, forgot to put restore directions.

In case your TL gives you issues, here is how you revert
change bootlist to hdisk0 (bootlist -m normal hdisk0)
reboot
alt_diskinstall -X (this will clean up the hdisk1 image, and clean up ODM entries)

HTH

 

[blasvinas]

Why don't you just apply the updates and then if you have any problems just reject the changes?

 

[Mag0007]

Yes, I can do that too, but never did, or really know how functional that is...

 

[columb]

Just my two-penny worth.

I administer a number of AIX boxes, mostly at AIX 5.1 but we still have a few AIX 4.3.3 systems. I never break the mirror for ML upgrades or backups. I have never restored any of the mksysb backups on our live servers, I hope I never have to(!) but I regularly restore a 'vanilla' mksysb onto my dev system without any problems.

For procedural reasons I'm forced to install all software, including ML upgrades, as 'APPLIED' rather than 'COMMITTED' to allow for easy rollback. We tent to commit one set of software just before we install the next.

What I'm experimenting with is alt_disk_install for migrating AIX 5.1 to AIX 5.2 (or hopefully AIX 5.3). This is the only time I'd break the mirror.

Ceci n'est pas une signature
Columb Healy

 

[bi]

And here is what we do where I work:

Usually, we just apply the ML/TL without unmirroring. But if it is a production system and they can't take a long outage for installing the update, we do an alt_clone for the update. (Yes, I know you can install software while the system is in use, but I don't like to do it on production.)

Unfortunately, we didn't do an alt_clone on a system that has a DB2 database and didn't discover until it was too late that 5.3 TL5 breaks DB2.

 

[DukeSSD]

You should also take care these days with installing updates as applied - with the TL updates some new filesets are included and they will only install as commited - so you can't back out....

 

[Mag0007]

You should also take care these days with installing updates as applied - with the TL updates some new filesets are included and they will only install as commited - so you can't back out....

Thats a good reason to unmirror and apply the ML, incase you can't revert back, just boot of old disk

 

[DukeSSD]

Mag0007, I totally agree, and three way mirroring will save you if the alt install has a problem and you have a hardware problem on one of the remaining disks.

Don’t forget you are exposed from the point the mirror is broken and the upgrade starts if you only had a two way mirror.

 

[zaxxon]

@DukeSSD

The last restore of a mksysb is was some years ago but I remember I had no problem at all. I was cloning a box from a mksysb and a savevg via tapes.
It was AIX 4.3.3 for sure.

laters
zaxxon

 

[zaxxon]

Forgot to add, the rootvg was mirrored on hdisk0 and 1 of course. Also our service representatives never unmirrored a VG when applying a ML or when getting a mksysb. I never heared of that in the last 6 years - it's the 1st time I heared that in this post here; totally new for me.

laters
zaxxon