tsm备份报错

环境：AIX 5.3
        tsm 6.2
        oracle11g
问题描述：
# ls
bkdb_bprod.log   bklog_bprod.log  expirebprod.log
# more bkdb*
Recovery Manager: Release 11.2.0.1.0 - Production on Tue Jun 14 23:00:00 2011
Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.
connected to target database: BPROD (DBID=856828653)
connected to recovery catalog database
RMAN> run {
2> allocate channel ch1 type 'SBT_TAPE' parms  'ENV=(TDPO_OPTFILE=/usr/tivoli/tsm/client/oracle/bin64/tdpo_bprod.opt)';
3> allocate channel ch2 type 'SBT_TAPE' parms  'ENV=(TDPO_OPTFILE=/usr/tivoli/tsm/client/oracle/bin64/tdpo_bprod.opt)';
4> backup incremental level 0 format 'inc0_%d_%s_%p_%T' filesperset 20 database tag levelbackup0;
5> backup current controlfile format 'ctl_%d_%T_%s_%p';
6> sql 'alter system archive log current';
7> release channel ch1;
8> release channel ch2;
9> }
10>
11>
allocated channel: ch1
channel ch1: SID=255 device type=SBT_TAPE
channel ch1: Data Protection for Oracle: version 5.4.1.0
allocated channel: ch2
channel ch2: SID=319 device type=SBT_TAPE
channel ch2: Data Protection for Oracle: version 5.4.1.0
Starting backup at 14-JUN-11
channel ch1: starting incremental level 0 datafile backup set
channel ch1: specifying datafile(s) in backup set
input datafile file number=00005 name=/bi/app/oracle/oradata/bprod/BIEE.DBF
input datafile file number=00007 name=/bi/app/oracle/oradata/bprod/INFAREP.DBF
input datafile file number=00009 name=/bi/app/oracle/oradata/bprod/BIEE2.DBF
input datafile file number=00011 name=/bi/app/oracle/oradata/bprod/INFAREP1.DBF
input datafile file number=00004 name=/bi/app/oracle/oradata/bprod/users01.dbf
input datafile file number=00002 name=/bi/app/oracle/oradata/bprod/sysaux01.dbf
channel ch1: starting piece 1 at 14-JUN-11
channel ch2: starting incremental level 0 datafile backup set
channel ch2: specifying datafile(s) in backup set
input datafile file number=00006 name=/bi/app/oracle/oradata/bprod/INFADOMAIN.DBF
input datafile file number=00008 name=/bi/app/oracle/oradata/bprod/BIEE1.DBF
input datafile file number=00010 name=/bi/app/oracle/oradata/bprod/INFADOMAIN1.DBF
input datafile file number=00003 name=/bi/app/oracle/oradata/bprod/undotbs01.dbf
input datafile file number=00012 name=/bi/app/oracle/oradata/bprod/undotbs02.dbf
input datafile file number=00001 name=/bi/app/oracle/oradata/bprod/system01.dbf
channel ch2: starting piece 1 at 14-JUN-11
channel ch1: finished piece 1 at 14-JUN-11
piece handle=inc0_BPROD_3806_1_20110614 tag=LEVELBACKUP0 comment=API Version 2.0,MMS Version 5.4.1.0
channel ch1: backup set complete, elapsed time: 00:02:35
RMAN-03009: failure of backup command on ch2 channel at 06/14/2011 23:25:58
ORA-19502: write error on file "inc0_BPROD_3807_1_20110614", block number 1 (block size=8192)
ORA-27030: skgfwrt: sbtwrite2 returned error
ORA-19511: Error received from media manager layer, error text:
   ANS1312E (RC12)   Server media mount not possible
channel ch2 disabled, job failed on it will be run on another channel
channel ch1: starting incremental level 0 datafile backup set
channel ch1: specifying datafile(s) in backup set
input datafile file number=00006 name=/bi/app/oracle/oradata/bprod/INFADOMAIN.DBF
input datafile file number=00008 name=/bi/app/oracle/oradata/bprod/BIEE1.DBF
input datafile file number=00010 name=/bi/app/oracle/oradata/bprod/INFADOMAIN1.DBF
input datafile file number=00003 name=/bi/app/oracle/oradata/bprod/undotbs01.dbf
input datafile file number=00012 name=/bi/app/oracle/oradata/bprod/undotbs02.dbf
input datafile file number=00001 name=/bi/app/oracle/oradata/bprod/system01.dbf
channel ch1: starting piece 1 at 14-JUN-11
channel ch1: finished piece 1 at 14-JUN-11
piece handle=inc0_BPROD_3808_1_20110614 tag=LEVELBACKUP0 comment=API Version 2.0,MMS Version 5.4.1.0
channel ch1: backup set complete, elapsed time: 00:02:25
Finished backup at 14-JUN-11
Starting backup at 14-JUN-11
channel ch1: starting full datafile backup set
channel ch1: specifying datafile(s) in backup set
including current control file in backup set
channel ch1: starting piece 1 at 14-JUN-11
channel ch1: finished piece 1 at 14-JUN-11
piece handle=ctl_BPROD_20110614_3809_1 tag=TAG20110614T232827 comment=API Version 2.0,MMS Version 5.4.1.0
channel ch1: backup set complete, elapsed time: 00:00:03
Finished backup at 14-JUN-11
Starting Control File and SPFILE Autobackup at 14-JUN-11
piece handle=c-856828653-20110614-01 comment=API Version 2.0,MMS Version 5.4.1.0
Finished Control File and SPFILE Autobackup at 14-JUN-11
sql statement: alter system archive log current
released channel: ch1
released channel: ch2
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of release command at 06/14/2011 23:28:44
RMAN-06012: channel: ch2 not allocated
Recovery Manager complete.


问题出在什么地方？如何解决？