RMAN FILESPERSET

I'm a bit confused by the default for filesperset. I ran the following yesterday ....

run
{

allocate channel c1 device type sbt format 'df_%t_%s_%p' maxpiecesize=2048M PARMS="SBT_LIBRARY=/opt/oracle/dbserver/9.0.1/lib/libobk.so, ENV=(TDPO_OPTFILE=/opt/tivoli/tsm/client/oracle/bin/tdpo.opt)"; backup database;
backup current controlfile;
release channel c1;
}

There were 245 datafiles in the database. RMAN made the following backup sets

   BS_KEY COUNT(B.FILE#)
---------- --------------

      9623             63
      9727             64
      9810             64
      9892             35
      9893              4
      9894              4
      9895              6
      9896              5
           --------------
sum                   245

As I understand it the default for filesperset is the lesser of 64 or the number of input files / the number of channels.
As there was only one channel I would have expected 3 backup sets of 64 files and one of 53 channels.

Today I ran against the same target database

run
{

allocate channel c1 device type sbt format 'df_%t_%s_%p' maxpiecesize=2048M PARMS="SBT_LIBRARY=/opt/oracle/dbserver/9.0.1/lib/libobk.so, ENV=(TDPO_OPTFILE=/opt/tivoli/tsm/client/oracle/bin/tdpo.opt)"; allocate channel c2 device type sbt format 'df_%t_%s_%p' maxpiecesize=2048M PARMS="SBT_LIBRARY=/opt/oracle/dbserver/9.0.1/lib/libobk.so, ENV=(TDPO_OPTFILE=/opt/tivoli/tsm/client/oracle/bin/tdpo.opt)"; backup database skip readonly;
backup current controlfile;
release channel c1;
release channel c2;
}

There are 92 read write datafiles. I would have expected the job to be divided into two backup sets with 46 files each.

Instead I got

    BS_KEY COUNT(B.FILE#)
---------- --------------

     10704              2
     10705              2
     10721              2
     10722              2
     10723              2
     10724              2
     10725              2
     10726              2
     10727              2
     10728              2
     10765             33
     10766              4
     10767              2
     10768              1
     10769              1
     10770              1
     10771              1
     10772              1
     10773              1
     10774              1
     10775              1
     10776              1
     10777              1
     10778              1
     10779              1
     10780              2
     10781              1
     10782             18
           --------------
sum                    92
-------------------------------------------------------------------------------------------------------------------------

Any guesses as to why so many backup sets are being created.

Ian MacGregor
Stanford Linear Accelerator Center
[EMAIL PROTECTED]

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: MacGregor, Ian A.
  INET: [EMAIL PROTECTED]

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).