Gerald,
If there is more than one channel allocated for the recovery process, then
it is possible that a restore will use more than one drive. For example, if
you allocate 4 channels to the recovery of the database, have 4 drives, and
all of the data is spread across 4 tapes, then you might run into tape
contention. The files that one channel may be using maybe be located on 1
tape and another channel is trying to restore from the same tape. The 2nd
channel will go into a media wait until this tape is freed up.
But if you are the lucky person that doesn't have all the data spread
across 4 tapes ( i.e. all 4 channels are using 4 different tapes), then all
4 can be restoring at the same time. I just got back from a disaster
recovery test where this exact thing happened. Sometimes the channels would
be waiting on the same tape and there would be media waits and other times
3 or 4 sessions would be using 3 or 4 tape drives. But, just note, that we
are using this in junction with RMAN. So that is where the "channel"
terminology is coming from. Hope this helps.
Regards,
Sean M. English
Distributed Support Services/ADSM
IBM Global Services South, Charlotte, NC
Experience is the worst teacher. It always gives the test first and the
instructions afterward.
"Joshua S. Bassi" <[EMAIL PROTECTED]>@VM.MARIST.EDU> on 09/11/2000
05:05:32 PM
Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]>
Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
cc:
Subject: FW: multiple tape drives
By default it should use 1 tape drive for an Oracle database restore.
Take a look at the installation manual and I am sure you will find
an option for the TDP for Oracle restore process to use as many tape
drives as you give it.
--
Joshua S. Bassi
Senior Technical Consultant
Symatrix Technology, Inc.
[EMAIL PROTECTED]
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED]]On Behalf Of
Gerald Wichmann
Sent: Monday, September 11, 2000 12:58 PM
To: [EMAIL PROTECTED]
Subject: multiple tape drives
In the case of a ibm3494 with 4 tape drives, what happens in the case of a
restore as far as the way TSM utilizes those drives? Will it take advantage
of the fact that there are 4 tape drives and mount 4 tapes to restore
quicker (assuming data is on 4 different tapes)?
For example what if I have an Oracle database with � a Terabyte of data
backed up to my TSM server. Obviously this data is going to be across
multiple tapes. Now when it comes time to do a restore, how many drives
will
it use to do the restore or what factors determine this?
Thanks
Gerald Wichmann
RS Engineer
Sansia System Solutions
408-844-8893 work
408-844-9801 fax
