Re: rman backup to tape

From: Jared Still <jkstill_at_gmail.com>
Date: Wed, 6 Jan 2010 09:01:16 -0800
Message-ID: <bf46381001060901p55aad705oe40da621acbb7c57_at_mail.gmail.com>

On Wed, Jan 6, 2010 at 5:32 AM, Nagaraj S <nagaraj.chk_at_gmail.com> wrote:

> Good Morning All,
>
>
> I have clarification on rman backup to tape. Suppose if backup team
> increase the netbackup streams from 2 to 8, will it decrease the database
> backup completion time window? And also how to make changes on rman script
> to configure the new streams build by backup team and how rman can
> communicate to backup each stream data’s on each tapes separately... Thank
> You
>
>

If there are 8 drives available, then it may decrease the time required for a backup.
If the network from the server to the tape library doesn't have the bandwidth to
accommodate that much data, then the backups may actually take longer than with 2 drives.

This is because tapes must be kept streaming to be efficient. When tape drives run out of data to write, they stop and rewind. When more data needs to be written, the tape drive must then seek to where it left of writing.

Here's an article on the topic:
http://www.computerworld.com/s/article/93057/Slow_down_those_streaming_tape_drives

Increasing the number of drives in use will also make those drives unavailable for other backup jobs.

Increasing the number of drives will also increase the number of tapes that must be vaulted (sent offsite)

The real question is: Did the backup team do their homework when deciding to increase the number of drives from 2 to 8?

Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist Oracle Blog: http://jkstill.blogspot.com Home Page: http://jaredstill.com

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Received on Wed Jan 06 2010 - 11:01:16 CST