topic snap shot backups in Operating System - HP-UX

snap shot backups

Avadhoot_4 — Tue, 01 Oct 2002 06:10:12 GMT

Hi !!!

We are taking OS partition backups using snapshot method . I am planning to take Database backup using same ( Databse is around 100GB ) other than Cold backup . is it worth ? Anybody
tried this ?

Thanks
Avadhoot

Re: snap shot backups

Stefan Farrelly — Tue, 01 Oct 2002 06:24:56 GMT

Weve tried this and as long as you have space for the snapshot, and you can 'freeze' the database (stop updates while the snapshot is completing) then consistency should be ok. Weve tried this a lot and had problems with database consistency as you MUST freeze or stop writes to the DB while the snapshot runs, and the DB must be in archive log mode (again for consistency reasons) otherwise you may not be able to recover your database when needed.
For this reason we eventually dropped it and went for online hot backups using RMAN.

Re: snap shot backups

Avadhoot_4 — Tue, 01 Oct 2002 07:31:29 GMT

Hi Stefan ,

We are taking the backups by Rman online using HP Omniback
. But we have seen lots of
problems during the restoration of online backup .so We have started Cold backup.If i use pre-execute and post execute option using omniback then also there will be consistency problem ? What do
u think ?

Regards
Avadhoot

Re: snap shot backups

Stefan Farrelly — Tue, 01 Oct 2002 07:40:28 GMT

We also use Omniback and online backups - Omniback talks directly to Oracle and backs up 'hot' or online. Weve used this a lot and it works fine - even restores. A lot of customers worldwide use this method and its reliable. I think you need to look into what your problems are restoring.

eg. RMAN db itself needs to be backed up cold in order to restore successfully (if you need to restore RMAN on say a different server). Is your db in archive log mode ? Its recommended your dbs are.

Re: snap shot backups

Christian Gebhardt — Tue, 01 Oct 2002 07:59:48 GMT

Hi
we are using a similar backup with BCV-devices from EMC:
- building a mirror from the running database
- split the mirrored devices
- write the splitted devices to tape

We had a lot of problems, but now it works.
The major problem was that the freeze-command from oracle doesn't work via sqlnet.
To prevent the database to write to the datafiles during the split we do a "begin backup" on all tablespaces a "archive log" and after that we split the logical volumes. It is very important to have datafiles, redologs and archived redologs on separate lvols and split them in this order.

The database you'll get on the split-devices is consistent and need no crash recovery to come up.

Christian

Re: snap shot backups

harry d brown jr — Tue, 01 Oct 2002 11:02:33 GMT

Avadhoot,

OS snapshot backups will help you restore INDIVIDUAL files, but it's not going to help you RECOVER a failed root disk. You should only be using ignite: make_tape_recovery.

get a newer version here:
http://www.software.hp.com/products/IUX/download.html

As for the database, if it's oracle you should be putting the database into hot backup mode while performing a snapshot.

live free or die
harry