RE: Oracle DB Backups on SAN with ALTER SYSTEM SUSPEND

[Hemant K Chitale]

We want true server-less backups.  I know that RMAN's overhead is [much] lower
than that of the ALTER TABLESPACE BEGIN/END BACKUP but the
Snapshot method in a SAN [akin to splitting and resilivering a mirror, in 
some ways]
should be much faster.  The database is in BACKUP mode only for the time it
takes the SAN to create the Snapshot which, I've been told, is seconds or 
minutes,
irrespective of the size of the database.  [Of course, there will be some 
time lag
between the first ALTER TABLESPACE <tbs> BEGIN BACKUP and the
ALTER SYSTEM SUSPEND command when the database will be doing a
Checkpoint at each Tablespace, and writing more Redo for transactions upto
the ALTER SYSTEM SUSPEND and will the END BACKUPs are still being issued.]

And I cannot use RMAN with the Snapshot method.  I must SUSPEND the database
and RMAN does not support that.
See 
http://download-west.oracle.com/docs/cd/A87860_01/doc/server.817/a76993/osbackup.htm#4233
"Making Backups in Suspend Mode"  in Chapter 4 "Performing Operating System 
Backups"
of the 8i Backup and Recovery Guide.

Hemant

At 05:38 AM 26-03-03 -0800, you wrote:
Hemant - If you've got to rework your backup script anyway (and retest it),
why not consider switching to RMAN at this time? In my experience,
negligible interference with production during a hot backup.
Dennis Williams
DBA, 40%OCP, 100% DBA
Lifetouch, Inc.
[EMAIL PROTECTED]
-----Original Message-----
Sent: Tuesday, March 25, 2003 10:49 PM
To: Multiple recipients of list ORACLE-L


Some of my databases will be migrating to a SAN.
Currently, I run hot backups to disk using the
ALTER TABLESPACE <tbs> BEGIN BACKUP ;
host cp <file> <target>;
ALTER TABLESPACE <tbs> END BACKUP
On a SAN, where the vendor promises server-less backups
using Snapshots, I guess I would have to issue the
commands :
ALTER TABLESPACE <tbs1> BEGIN BACKUP
..
..
ALTER TABLESPACE <tbsN> BEGIN BACKUP
ALTER SYSTEM SUSPEND
....> take a "snapshot"
ALTER SYSTEM RESUME
ALTER TABLESPACE <tbs1> END BACKUP
..
..
ALTER TABLESPACE <tbsN> END BACKUP
Would that be right ?  What are real-world experiences
[bugs / time required for the SUSPEND/RESUME, actually
flushing all I/O to the disks] ?
The SAN will be a Hitachi 9970 sold by Sun.
The databases will be 8.1.7 32-bit / 64-bit on Solaris 8.
Hemant K Chitale
http://hkchital.tripod.com
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