RE: clarion san split
- From: "Jesse, Rich" <Rich.Jesse@xxxxxxxxxxxxxxxxx>
- To: <stmontgo@xxxxxxxxx>, <Oracle-L@xxxxxxxxxxxxx>
- Date: Thu, 24 Feb 2005 12:31:17 -0600
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:
1) Disable the existing logical copy (the split).
2) Throw all the DB's tablespaces into backup mode.
3) Enable the logical copy.
4) End backup mode for all tablespaces.
5) 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:
1) TEST
2) TEST!
3) TEST!!
And you want to be my latex salesman? ;)
HTH! GL! Enjoy!
Rich
Rich Jesse System/Database Administrator
rich.jesse@xxxxxxxxxxxxxxxxx QuadTech, Sussex, WI USA
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[ mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of art vandelay
Sent: Wednesday, February 23, 2005 10:16 PM
To: Oracle-L@xxxxxxxxxxxxx
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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