RE: ****** RMAN backup for multi TB databases ******

  • From: Sam Reddy <iamanoracledba@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Mon, 23 Aug 2004 13:39:13 -0700 (PDT)

Hi Stephen,
 
Thank you very much for the details! Much appreciated!
 
When you recollect the rman parameter that sets how big the chunks of data are 
that it
sends to Networker please let me know.
 
Best regards,
Sam
Stephen.Lee@xxxxxxxx wrote:

I don't have anything as big as your situation, but I do have a box on which
the rman backup sets for full backup total between 500 - 600 Gb. The
limitation on speed here is the rate at which data can be tape written to
the tape drives; and this depends on the number of drives and the number of
I/O interfaces to the drives. If you are writing directly to tape, then you
can experiment with the number of rman channels to open to get the writes to
distribute over the drives and keep all of the drives busy writing. There
is also an rman parameter that sets how big the chunks of data are that it
sends to Networker. I forgot what it is.

Because of concerns about restore time when restoring directly from tape, we
now run rman to backup to a 1.8 Tb filesystem created for this purpose, then
use a ksh (We don't need no stinkin' Perl) script to copy the files to tape
via Networker and delete the previous day's backup. The archived log
backups get copied first. Our backup times run 3 hours to backup to disk
and 7 - 9 hours to copy to four tape drives on two SCSI interfaces. I have
maxpiecesize set to 5 GB for the datafile backups so that the I/O gets
distributed more or less evenly among the tape drives. Archived log backups
don't have maxpiecesize set because those backup sets usually total around
15 - 25 Gb.

The script for sending to files to tape can be found here:
http://integrid.info/tape_copy.ksh

NOTE: One thing that should be fixed with the script -- one of these days
when I get around to it (oh yeah, sure) -- is that while the script checks
to see if it is already running with at least one of the command line args
and exits if it is, it will run (I think) if there are no common command
line args between the two commands. HOWEVER, both running copies will use
the same log file. (I'm pretty sure the e-mail files will be unique.) I
really should do something about that ... some time ... before the Vogons
get here and bulldoze the planet away.

>-----Original Message-----
>I am concerned about 
>backup time with full/cumulative/ incremental backups when 
>RMAN is used in conjunction with Legato networker.
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