Re: new database server build - sanity check

From: Ryan January <>
Date: Tue, 29 Jan 2013 17:15:09 -0600
Message-ID: <>

I would never trust a snapshot as a sole means of backup. They still allow for single points of failure. Backups are all about redundancy; something that snapshots do not inherently provide.

As an example: if you have a storage (SAN, RAID Controller, or disk) failure your "backup" was on the same media as your primary storage. You've potentially lost your database.

As long as you're aware of the restrictions/penalties which come along with snapshots they can be wonderful tools used in an overall backup or DR strategy.

The snapshot can be seen as a point in time copy of the filesystem. As such, you would treat the database as you would for any database backup at the filesystem level. If the database is open you would put it in backup mode, snap the file system, then end backup mode. Creating a live database from the snapshot would also be similar to recovering a database from a file system level backup.

While this process technically doesn't require additional software, it's a relatively time intensive process. If this happens on a regularly you will want it automated. This lends itself to another great excuse for backup/recovery testing.

I happened to run across a related article yesterday. It's mostly an rman sales speech, but does bring up some valid points.

On 01/29/2013 12:02 PM, Chris King wrote:
> Sounds like ZFS snapshots could be a good backup or even a DR strategy? Is extra/specific software required to take/use snapshots for live/open Oracle databases? Or does the database have to be closed to do this?
> **
> The snapshot capabilities can be a nice feature. You can snap a live database and restore it
> back
> within moments -- eliminating the time needed for an RMAN restore.
> Having said that, I would look into testing some things
> -- perhaps Google "ZFS evil tuning guide" -- Note however, that there
> are also websites out there that discount much of what is in the guide,
> essentially saying to leave the defaults or most of them, hence some testing
> first. The foundation you lay will be
> the one you will be using.
> Joel Patterson
> Database Administrator
> 904 727-2546
> --

Received on Wed Jan 30 2013 - 00:15:09 CET

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