RE: clarion san split

From: Jesse, Rich <Rich.Jesse_at_quadtechworld.com>
Date: Thu, 24 Feb 2005 12:31:17 -0600
Message-ID: <FB5D3CCFCECC2948B5DCF4CABDBE6697023523@QTEX1.qg.com>

We're using an IBM FAStT 900 SAN, but yes we do use a SAN split (known as Flash Copy on the FAStT) to backup our l'il 40GB 9.2.0.5 DB. I'm not sure what advantage RMAN would have for this, but our nightly hotbacks go a little something like this:

Disable the existing logical copy (the split).
Throw all the DB's tablespaces into backup mode.
Enable the logical copy.
End backup mode for all tablespaces.
Backup logical copy to Tivoli backup system located in the next county (our archive logs are handled separately).

Steps 1-4 take about 20 seconds, with some padded sleeps in there for CYA safety (sometimes filesystems take an extra second or two to "really" unmount a logical volume). Step 5 runs at about 50-60GB/hour for us. Our locations are connected via shared 1GB fiber, I believe.

One very important thing to remember about this is that in order to maintain a consistent "snapshot" of what the DB looked like at the time of backup, the SAN needs to make a copy of the data blocks (SAN blocks, not Oracle blocks) before changing that block for the first time. This only needs to happen as long as your snapshot exists. This extra copy can cause a write performance penalty. Also, the SAN needs to copy this data block to somewhere, and that somewhere is defined by the SAN Administrator. If you don't provide enough space to save all the blocks that can change while the backup's running, the snapshot/split/fastcopy will most likely fail, causing your backup to fail (among other things). Lord knows what'll happen on NT. I wasn't very confident Windohs would handle it, but didn't care because we're on HPUX.

There are three things to keep in mind when changing your backup strategy:

TEST
TEST!
TEST!!

And you want to be my latex salesman? ;)

HTH! GL! Enjoy!

Rich

Rich Jesse                        System/Database Administrator
rich.jesse_at_quadtechworld.com      QuadTech, Sussex, WI USA

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[ mailto:oracle-l-bounce_at_freelists.org]On Behalf Of art vandelay Sent: Wednesday, February 23, 2005 10:16 PM To: Oracle-L_at_FreeLists.org
Subject: clarion san split

our nt admin is trying to push this emc clarion SAN split on ud for backups...anyone using this?

Also as an aside,we take rman backups to disk producing about a 130gb backupset, from there the nt admins backup to tape. My rman backup takes 45 mins and the backups to tape takes 9 hours using LTO 2 over the newtork. Is it me or does this seem like a long time. During the backup to tape the whole network goes wooooosh as the available bandwith is being taken up by the backups.

tks

steve
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http://www.freelists.org/webpage/oracle-l Received on Thu Feb 24 2005 - 13:33:39 CST