Have you, as a TSM or NetBackup backup solutions user, noticed multiple entries in LIST HISTORY BACKUP for each of your successful DB2 backups, each with a different image sequence number, and wondered why? If you are using multiplexing DB2 backup software such as TSM or NetBackup, DB2 LIST HISTORY BACKUP will show a separate entry for every channel/session used by the backup. Each entry, distinguished by unique 3-digit Sequence Number (( as found in the image name format
DB_alias.Type.Inst_name.NODEnnnn.CATNnnnn.timestamp.Seq_num
[REFERENCE] )) corresponds to one channel or session. An 8-channel multiplex will therefore show 8 entries in LIST HISTORY BACKUP for every single successful backup operation.

A simple thing, but it does not seem to be well documented.

Thanks to Surbhi Gupta of Cognizant for pointing this out.

Here is an example of a typical LIST HISTORY BACKUP for a backup using 4 sessions and NetBackup with 4 channels:

List History File for mydb

Number of matching file entries = 4

Op Obj Timestamp+Sequence Type Dev Earliest Log Current Log  Backup ID
-- --- ------------------ ---- --- ------------ ------------ --------------
B  D  20090206020335001   N    O  S0030352.LOG S0030352.LOG
----------------------------------------------------------------------------
Contains 10 tablespace(s):

00001 SYSCATSPACE
00002 USERSPACE1
00003 MYDB8KDATASPACE1
00004 MYDB8KINDEXSPACE1
00005 MYDB8KLOBSPACE
00006 MYDB32KDATASPACE
00007 MYDB32KINDEXSPACE
00008 MYDB32KLOBSPACE
00009 MYDB4KDATASPACE1
00010 SYSTOOLSPACE
----------------------------------------------------------------------------
Comment: DB2 BACKUP MYDB ONLINE
Start Time: 20090206020335
End Time: 20090206043818
Status: A
----------------------------------------------------------------------------
EID: 36458 Location: /usr/openv/netbackup/bin/nbdb2.so64

Op Obj Timestamp+Sequence Type Dev Earliest Log Current Log  Backup ID
-- --- ------------------ ---- --- ------------ ------------ --------------
B  D  20090206020335002   N    O  S0030352.LOG S0030352.LOG
----------------------------------------------------------------------------
Contains 10 tablespace(s):

00001 SYSCATSPACE
00002 USERSPACE1
00003 MYDB8KDATASPACE1
00004 MYDB8KINDEXSPACE1
00005 MYDB8KLOBSPACE
00006 MYDB32KDATASPACE
00007 MYDB32KINDEXSPACE
00008 MYDB32KLOBSPACE
00009 MYDB4KDATASPACE1
00010 SYSTOOLSPACE
----------------------------------------------------------------------------
Comment: DB2 BACKUP MYDB ONLINE
Start Time: 20090206020335
End Time: 20090206043818
Status: A
----------------------------------------------------------------------------
EID: 36459 Location: /usr/openv/netbackup/bin/nbdb2.so64

Op Obj Timestamp+Sequence Type Dev Earliest Log Current Log  Backup ID
-- --- ------------------ ---- --- ------------ ------------ --------------
B  D  20090206020335003   N    O  S0030352.LOG S0030352.LOG
----------------------------------------------------------------------------
Contains 10 tablespace(s):

00001 SYSCATSPACE
00002 USERSPACE1
00003 MYDB8KDATASPACE1
00004 MYDB8KINDEXSPACE1
00005 MYDB8KLOBSPACE
00006 MYDB32KDATASPACE
00007 MYDB32KINDEXSPACE
00008 MYDB32KLOBSPACE
00009 MYDB4KDATASPACE1
00010 SYSTOOLSPACE
----------------------------------------------------------------------------
Comment: DB2 BACKUP MYDB ONLINE
Start Time: 20090206020335
End Time: 20090206043818
Status: A
----------------------------------------------------------------------------
EID: 36460 Location: /usr/openv/netbackup/bin/nbdb2.so64

Op Obj Timestamp+Sequence Type Dev Earliest Log Current Log  Backup ID
-- --- ------------------ ---- --- ------------ ------------ --------------
B  D  20090206020335004   N    O  S0030352.LOG S0030352.LOG
----------------------------------------------------------------------------
Contains 10 tablespace(s):

00001 SYSCATSPACE
00002 USERSPACE1
00003 MYDB8KDATASPACE1
00004 MYDB8KINDEXSPACE1
00005 MYDB8KLOBSPACE
00006 MYDB32KDATASPACE
00007 MYDB32KINDEXSPACE
00008 MYDB32KLOBSPACE
00009 MYDB4KDATASPACE1
00010 SYSTOOLSPACE
----------------------------------------------------------------------------
Comment: DB2 BACKUP MYDB ONLINE
Start Time: 20090206020335
End Time: 20090206043818
Status: A
----------------------------------------------------------------------------
EID: 36461 Location: /usr/openv/netbackup/bin/nbdb2.so64

Footnotes