Omniback doing Oracle hot backups

[Roger Sager_1]

G'day folks,

We use Omniback II version A.03.0 to backup our Oracle databases and the
Oracle Application software on our HP 9000 T600 server. The interest point is
that we always run a command in the crontab file to stop the oracle apps
concurrent managers, then shutdown all Oracle7 instances, then stop the
Listener. After this time the omniback time settings wakes up and proceeds to
do a cold backup. After the tape backup is completed, another crontab command
executes to start up all oracle databases, concurrent managers, and the
listener.

However, on one occassion the crontab stop procedure DID NOT execute and
omniback ran at the specified time and did, what appears is, a hot backup of
open Oracle instances.

Questions???

Has anyone else come across this?
Has anyone tried to restore sucessfully from one of these omniback "hot"
backups?
Does omniback "hot" backups work?

Cheers...Roger Sager

[Alan Riggs_1]

Oracel hot backups can work. However they require more than just leavin oracle
instances up while the data is backed up. What you have done is to backup data
files that are {potentially} still being written to. There is nothing to
prevent this, and you can even restore from those files. The problem will come
when you try ro apply the rolback logs to recover transactions posted since the
backup. Because transactions were posting during the backup, it is not
possible to simply identify a point in time (beginning of backup) and apply the
archive logs from there forward.

Oracle does provide scripts for their hotbackup utility whihc will place table
spaces into "hotbackup mode". When this is done, a separate rollback log is
maintained for the duration of the backup and then written into the archive
directory after backup has completed.

As a side note -- I use the omniback pre and post execution scripts to shutdon
and restart oracle. This avoids potential troubles like the one you found when
your cron job did not fire.

[Satar Naghshineh_1]

In order to have a hot backup in Oracle, you must be in archivelog mode and
before backing up the dataspaces, you have to issue the "alter tablespace begin
backup" command. Although datafiles are still being written to in this
situation, the header files are not updated untill after the "...End Backup"
command is issued.

If the database was open while the "offline" or "cold" backup was performed,
the backup is invalid and can not be guaranteed usuable in a recovery
situation.

Good Luck,
Satar

[John Cooper_12]

Roger,
In response to this and your next query about possible tar/cpio scripts:
We are currently using 10.20 HP-UX for Financials 10.7 SC and Oracle Gemms,
v7.3.3 of the RDBMS. We run as schedule of hot backups everyday, with a cold
backup on Saturday mornings. The database size is around 10Gb, which with the
other instances means that we copy around 35Gb to a DTL4000. This takes around
4hrs 30mins. I wrote the shell scripts to do this using vxdump as our database
files are in their own file systems. The hot backups are done to disk, then the
tape backup copies them later.

To check if your database is in Archivelog mode check the init.ora file for the
instance for the archive_log_start parameter set to true and query the
v$database view to check the actual log mode.
The v$backup view will give you the current status of any hot backups and the
time of the last backup status change.

Please note:
If you do implement archivelog mode then be prepared to allocate a fair amount
of space to the archivelog area. We currently have 1.5Gb allocated and can use
all of this in 8 hours at monthend.

If you would like more info on the backup scripts or the hot backup scripts
please send me an e-mail (I guess time differentials preclude the use of the
telephone!)

Good Luck!
John Cooper

[Phani Yenugu_1]

The backup that is done when the database was up without putting the database
in backup mode was no good. From Oracle point of view (I think), it is not
useful for restore.
The best way is to include your scripts in Omniback Pre and post exec to
shutdown and startup the database.
But, keep in mind, the omniback pre-exec and post-exec will be executed as
root. so you have to attach a script which calls another to do su to the owner
of the database to execute the oracle commands to shutdown and startup the
database.
Have questions, let me know.

[Samir Mohammed]

I am using Omniback II 3.0 to backup my Oracle7 and Oracle8 databases in hot
backup mode. Omniback libraries are linked with Oracle as follows.
Oracle7 with EBU and Oracle8 with RMAN. I have performed recoveries for both
Oracle8 and Oracle7 with complete success. Setting it up was quite some work,
but once completed, works like a charm. Backups in this manner are more
intelligent and quicker than cold backups. I have a 40GB production database
in Oracle8 takes 90 minutes to backup in hot mode. I even tested it in a
disaster recovery situation with Oracle8 and it was a success. Let me know if
you are interested in setting up such a configuration.

[Jim Campbell_7]

It is possible and we have also had success using the pre-exec and post-exec
scripts here at ansett to shutdown and startup the oracle 7.3.2.3 and 7.3.4.5
Datbases under HP Ux 10.20.

Question: When backing up Oracle Databases, have you ever come across "IPC Read
Error messages" from OMniback? (release 3.0)