Re: backup options

"Sean M" <smckeown_at_earthlink.net> wrote in message news:3D12BE3B.FA8C7CBA_at_earthlink.net

> This isn't entirely true... you can, if you're *very* careful and fully
> understand the Oracle recovery concepts, flip-flop between production ->
> standby -> production ad infinitum in pre-9i releases (back to 7.3 I
> believe). The process is too complex to describe in detail here, but if
> you do a search on "Graceful Switchover and Switchback for Oracle
> Standby Databases" in Metalink you'll find a white paper, written by
> Lawrence To, that describes a fully supported method of doing this. The
> basic idea is that the standby database is a exact backup of your
> primary. If you shutdown your primary cleanly, move the primary's
> online redo logs and recreate the standby's controlfile to look just
> like the primary's, and apply all archives, you can "fake out" Oracle
> into thinking the whole database has moved to a new machine. You never
> issue an "activate standby database" command, you never issue an "open
> resetlogs" command, so you don't have to rebuild/recopy anything.
>
> This paper effectively describes how to manually accomplish what 9i DG
> graceful switchover does for you automatically.
>
> Regards,
> Sean M

There's also a method using Oracle Standby Database and EMC's SRDF product. According to the EMC literature, you can get "No Data Loss" Standby Database with this configuration. Basically you have a Standby database with the usual setup at a remote site, using EMC disk. SRDF handles the Archive Redo Log transfer by writing to the remote disk at the same time it writes to the local disk on the primary server. The cool thing is, you also have an SRDF copy of the primary's control file and online redo logs on the Standby server, again they are kept up-to-date by SRDF writing to the original and copy at the same time. If you have a failure of the primary server, you follow the relatively simple procedure in the EMC doc's and the Standby is shutdown and uses the copy of the primary's control file and online redo logs. It essentially becomes the Primary database, as opposed to an "activated" standby.

We haven't actually done this yet, but hope to give a try in the next few months. I am waiting on the EMC infrastructure to get built up.

Later ....
Patrick

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