[Veritas-bu] Backup using more than one tape drive.

You didn't actually tell RMAN to use 5 tape drives.

Within RMAN you "allocate" a certain number of "channels" to be used for the
backup.  You give the channel a set of parameters to work within.  For
example, you might tell RMAN to use 5 channels and that each channel can be
no larger than 5 GB or contain more than 64 files.  When one of those 5
finishes, another will be created in it's place until everything that RMAN
was trying to backup has been completed.  Each one of these channels appears
as a separate job within NetBackup (e.g. different backup_id, job id within
Activity Monitor, etc.).  The file list for the backup job will contain a
single file with a unique name that was assigned to the channel by RMAN.

RMAN doesn't know or care about what NetBackup is doing with these jobs.  For
instance, you could have all 5 mux to the same tape drive or you could have
each one go to a different tape drive and RMAN doesn't know the difference.
RMAN keeps track of the file name it used for the channel and what Oracle
files are in this file.  NetBackup keeps track of where it put this file
(e.g. media id, mux, media server, etc.).

As others pointed out, what NetBackup does with this is controlled by the
combination of many things.
- max jobs per client (global attrib)
- max jobs per class
- schedule's media mux value (per drive)
- storage unit's max mux per drive
- retention of the job (unless you have allowed multiple retentions per
media... not recommended)

The "Allow Multiple Data Streams" option is not available in an Oracle type
class because it is not needed.  If you are doing cold backups outside of
RMAN (if you are using RMAN for "hots", I would also use it for the "colds")
with a standard class, this is what allows multiple streams from the client
at the same time.  Again, what NetBackup does with those streams (whether it
puts it on the same tape or different tapes) depends on the settings
mentioned above.


Scott Kendall
Hospital Products Division
Abbott Laboratories




 ecarr AT qwest DOT com
 Sent by: veritas-bu-admin AT Eng.Auburn DOT EDU
 02/13/2001 01:36 PM

   To: Veritas-bu AT mailman.eng.auburn DOT edu
   cc:
   Subject: [Veritas-bu] Backup using more than one tape drive.

Hi All, my question is in two parts ...

1) I am trying to backup a 500+ gig ORACLE database to my StorageTek L700
tape library using more than one tape drive!  The library has 6 fibre 9840
tape drives.  I have run a backup once but it only utilized one tape drive
and it took 26 hours!  I am wondering if there is a way to make it use all 6
drives in the library for the backup.  The machine that will be backing up
the database is a media server (not the master) and is connected directly to
the fibre network.  I am using NetBackup to run the backup (Standard Class)
not RMAN.  Both the Job and NetBackup have a maximum multiplex of 8.

2) Our Oracle Admin was trying to use RMAN to push a "HOT" Backup of the
same database and told rman to utilize 5 of the six tape drives, but it was
only using 1 for some reason!  Should I have the Media Multiplexing set to 1
on the ORACLE Class backup?  Any help with this would be appreciated!

Thanks

Ted Carr

_______________________________________________
Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu