Question: These errors started appearing in the db2diag.log files for a production DB2 database. I have a process to Manage DB2 db2diag.log files.The daily DB2 online backup was successful – but failed to archive log.

2012-04-20-11.15.52.720713+060 E1088884685E547 LEVEL: Error
PID : 13535 TID : 47411049261376PROC : db2sysc 0
INSTANCE: db2misc NODE : 000
EDUID : 24 EDUNAME: db2logmgr (db1) 0
FUNCTION: DB2 UDB, data protection services, sqlpgArchiveLogFile, probe:3160
MESSAGE : ZRC=0x86100025=-2045771739=SQLP_MEDIA_VENDOR_DEV_ERR
 "A vendor device reported a media error."
DATA #1 : 
Failed to archive log file S0005908.LOG to TSM chain 2 from /db2inst1/logs/db1/NODE0000/.

Answer:  1)  check the configuration on the database are correct. LOGARCHMETH1 = TSM , LOGRETAIN=RECOVERY. And you’re not  getting the DB2 SQL2413N – Online backup is not allowed  error

2)       Break connections to the database  and take a full DB2 offline backup

Db2 QUIESCE DATABASE IMMEDIATE FORCE CONNECTIONS
Db2 BACKUP DATABASE MYDBI USE TSM