Tape Backup on mirrors

[Igaduma]

Hi all,

Something i've been thinking about...but am a little reluctant to really try it...on a production machine...

I want to level 0 backup a mirrored root system, is it enough to take a backup of the mirror and in case of recovery put that back on both disks, also on the sub ?
Or best bet is to actually take 2 backups of the mirror & the submirror ?

Thanks,
I

 

[dxm]

We use DIsksuite for mirroring and tape backups... We take one of the submirrors offline back it up and then put it back online... hope that helps.

 

[Igaduma]

Hi,

I'm using disksuite too, I was wondering if it's possible to detach the mirror while running & doing a backup without shutting down to single user ?
Once it's resynced & state is OK, detach from mirror, backup to tape, re-attach to mirror, let it sync back and bob would be my uncle right ?

Iga

 

[cgswong]

Iga,

It's possible to detach the mirror while running and do a backup without shutting down to single user (there will be no activity on the detached disk), then re-attach and resync. However, remember that while the disk is detached you only have one disk and if anything goes wrong with that disk you'll have to use the detached disk (or restore from tape) which would not be as current. The chances of this happening are small so you should be okay, just so as you are aware. An ideal setup would be a 3 mirror RAID so while one is detached you are still covered, but this is more expensive and not really necessary unless you're truly paranoid and require a total solution.

 

[Igaduma]

Hi wongyc2k,

.....totally paranoid!
ROFLMAO!
And backing up to two different tape devices, each connected to different controllers to minimize possible data corruption!!

I'll go for running the system on 1 disk

Thanks for the info,

cheers,
Iga

 

[Igaduma]

Hi list,

Another thing about this:

I have a metadb on the root disk, slice 6, a 250Mb unused slice, only for the metadb.
This slice doesn't have an ufs.

Since I can't use the ufsdump because it gives me a fsck error (which I presume is correct, since I didn't create a ufs on it, just selected that empty slice as the metadb)

Could I use
cp /dev/rdsk/c0t0d0s6 /dev/mt/0
I would guess it just takes a whole copy of the slice on tape, afterwards in case of doom & gloom I could go for a
cp /dev/mt/0 /dev/rdsk/c0t0d0s6

right ?

I

 

[Igaduma]

Hi List,

When talking yesterday to a sun support guy he told me that when using disksuite and ufsdump you don't need to detach the submirror,
apparently ufsdump, part of the OS, takes care of that, when backing up the submirror doesn't sync to the mirror.

Nice to know...keep them tapes coming!


Iga

 

[Guest_imported]

The ufsdump will work for you for the OS backup but what about keeping the database in sync? If you do that break the mirror and do a backup off of it the database should startup when you do your restore. It doesn't matter from the system admin point of view but it saves the dba some work. Just something to think about.