Re: cron backups on RAC

  • From: David Robillard <david.robillard@xxxxxxxxx>
  • To: Don Morse <dmorse2@xxxxxxxxx>
  • Date: Fri, 15 Jun 2012 08:55:33 -0400

Hi Don,

> To list::  I'm configuring rman backups for our first RAC deployment, 
> hopefully to be live in September.
> In the past, with single-instance Oracle, I have used cron to schedule daily 
> backups from the database server.
> We have always licensed Tivoli for Oracle from IBM, this gives rman the 
> interface to our Tivoli tape library.
> Now that we have a 3-node cluster, I'm trying to decide how to schedule 
> backups; one of the nodes will be the preferred server,
> others will run the rman job only if the others are not available. I have 
> seen reference to using dbms_scheduler,
> but this would not work if we wanted to run an offline backup. I would 
> appreciate any ideas.

I used to be in the exact same situation as you when we deployed our
first RAC. I've solved the issue by building a seperate machine which
I configured as our RMAN server. That machine ran a single Oracle
instance used exclusively for RMAN. (I checked with my Oracle rep and
that machine didn't need licenses because it's used only for RMAN :)

The RMAN server's crontab is used to schedule all other Oracle
instance backups. By using 11.2 RAC SCAN FQDN in the tnsnames.ora
files, I could always backup our RAC clusters even if a node on those
clusters was down. I created RMAN stored scripts to backup 9iR2, 10gR2
and 11gR2 databases. Those scripts created incrementally updated disk
based RMAN backupsets for all the clients. I also used RMAN to backup
the RMAN catalog to disk based backupsets. The client backupsets were
dumped on an NFSv3 share from the RMAN server (so one can imagine this
setup requires quite a lot of disk space, but disk is cheap, right?!
;o) I then used NetBackup to backup the entire RMAN server (along with
all the client's backupsets) to tape and then sent those encrypted
tapes off-site. It worked great!

But you have to keep an eye for the Oracle versions in that setup. As
the RMAN server can't be running a higher version than the client.
Well, no, it can, but you can't use an RMAN binary that's of a higher
version then the client you want to backup. For instance, I could
backup our 11gR2 RAC machines by using the RMAN server's 11gR2 rman
binary. But I couldn't do this for the 9iR2 and 10gR2 instances. For
those, I had to use their own lower versioned rman binaries. Using the
older binaries, I could still use the 11gR2 RMAN catalog running on
the RMAN server. Which meant that the 9iR2 and 10gR2 server's crontabs
were still used to initiate the backups : not the RMAN 11gR2 server's
crontab! Fortunately both of our RAC clusters were running 11gR2 so I
was ok.

The « Oracle Database Backup and Recovery User's Guide 11g Release 2 »
[*] and the following Metalink documents helped me build this setup.

Doc ID 1117597.1 - NFS options for 11.2.0.2 RMAN disk backups on Linux 64-bit.
Doc ID 360416.1 - Oracle10g / 11g - Getting Started with Recovery Manager (RMAN)
Doc ID 351455.1 - Oracle Suggested Strategy & Backup Retention
Doc ID 303861.1 - Incrementally Updated Backup In 10G

Let me know if you'd like more info.

> Thanks!

HTH,

DA+

[*] http://download.oracle.com/docs/cd/E11882_01/backup.112/e10642/toc.htm

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