Hello, please help with the following errors:

Recovery Manager: Release 10.2.0.4.0 - Production on Wed Jun 25 09:29:22 2008

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RMAN> connect target *
2> run {
3> allocate channel ch1 type 'SBT_TAPE';
4> allocate channel ch2 type 'SBT_TAPE';
5> allocate channel ch3 type 'SBT_TAPE';
6> allocate channel ch4 type 'SBT_TAPE';
7>
8> backup
9> incremental level 1
10> format '%d_%U'
11> tag ETL
12> (database include current controlfile);
13>
14> release channel ch1;
15> release channel ch2;
16> release channel ch3;
17> release channel ch4;
18> }
19>
......................
channel ch4: starting piece 1 at 25-JUN-08
channel ch4: finished piece 1 at 25-JUN-08
piece handle=ETL_5sjjq6gc_1_1 tag=ETL comment=API Version 2.0,MMS Version 4.5.0.0
channel ch4: backup set complete, elapsed time: 00:34:21
channel ch4: starting incremental level 1 datafile backupset
channel ch4: specifying datafile(s) in backupset
including current control file in backupset
channel ch4: starting piece 1 at 25-JUN-08
channel ch4: finished piece 1 at 25-JUN-08
piece handle=ETL_5tjjq8gp_1_1 tag=ETL comment=API Version 2.0,MMS Version 4.5.0.0
channel ch4: backup set complete, elapsed time: 00:00:11
channel ch4: starting incremental level 1 datafile backupset
channel ch4: specifying datafile(s) in backupset
input datafile fno=00020 name=/etl/odb2/ETL/DEPENDENCY_TABLES01.dbf
input datafile fno=00023 name=/etl/odb2/ETL/LOB_DATA01.dbf
channel ch4: starting piece 1 at 25-JUN-08
channel ch4: finished piece 1 at 25-JUN-08
piece handle=ETL_5ujjq8h4_1_1 tag=ETL comment=API Version 2.0,MMS Version 4.5.0.0
channel ch4: backup set complete, elapsed time: 00:00:07
RMAN-03009: failure of backup command on ch3 channel at 06/25/2008 10:18:53
ORA-27192: skgfcls: sbtclose2 returned error - failed to close file
ORA-19511: Error received from media manager layer, error text:
The savefile_fini() call failed. (1:5:2)
ORA-19502: write error on file "ETL_5rjjq6g5_1_1", blockno 7915009 (blocksize=512)
ORA-27030: skgfwrt: sbtwrite2 returned error
ORA-19511: Error received from media manager layer, error text:
asdf_output_section1() failed
channel ch3 disabled, job failed on it will be run on another channel
channel ch4: starting incremental level 1 datafile backupset
channel ch4: specifying datafile(s) in backupset
......................
channel ch1: finished piece 1 at 25-JUN-08
piece handle=ETL_5pjjq6fr_1_1 tag=ETL comment=API Version 2.0,MMS Version 4.5.0.0
channel ch1: backup set complete, elapsed time: 01:09:50
channel ch2: finished piece 1 at 25-JUN-08
piece handle=ETL_5qjjq6fr_1_1 tag=ETL comment=API Version 2.0,MMS Version 4.5.0.0
channel ch2: backup set complete, elapsed time: 01:13:35
released channel: ch1
released channel: ch2
released channel: ch3
released channel: ch4
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on ch4 channel at 06/25/2008 11:07:32
ORA-27192: skgfcls: sbtclose2 returned error - failed to close file
ORA-19511: Error received from media manager layer, error text:
The NMO error message has been lost. Please set NSR_DEBUG_FILE and run NMO

Recovery Manager complete.