pajama

If a log file is archived and contains no open transactions, the DB2 database manager does not delete the file but renames it as the next log file when such a file is needed. This process improves performance because creating a new log file instead of renaming the file would require all pages to be written out to guarantee that the necessary disk space or other storage space is available.

The database manager retains up to 8 extra log files in the active log path for renaming purposes.

Aim is that there is existing log file can be used to rename when high workload comes:
(1) at that point the log consumption will become very quickly.
(2) creating new log file is a high cost operation since DB2 need to write to log file in advance, otherwise, the disk space may not be actually allocated to DB2.

You can collect "db2pd -db <database> -dpsdbcb" data.

Please provide the output file of db2pd command to IBM DB2 Service to check rename array for confirmation.

When the history information is not available for a backup image, the db2ckbkp utility can be used to identity if the backup was taken online or offline, and which logs are needed to rollforward the database.

You can use the db2ckbkp utility with the -h option and look for the "Backup Mode" parameter in the media header information. If the "Backup Mode" parameter is set to "0", the backup was taken offline; if it is set to "1", the backup was taken online. Furthermore, in case of an online backup, you can see if the logs are included by looking at the "Includes Logs" parameter.

=====================
MEDIA HEADER REACHED:
=====================
Server Database Name           -- SAMPLE
Server Database Alias          -- SAMPLE
Client Database Alias          -- SAMPLE
Timestamp                      -- 20100730130237
Database Partition Number      -- 0
Instance                       -- db2inst1
Sequence Number                -- 1
Release ID                     -- D00
Database Seed                  -- A05E5954
DB Comment's Codepage (Volume) -- 0
DB Comment (Volume)            --                               
DB Comment's Codepage (System) -- 0
DB Comment (System)            --                               
Authentication Value           -- -1
 Backup Mode                    -- 1
 Includes Logs                  -- 1
Compression                    -- 1
Backup Type                    -- 0
Backup Gran.                   -- 0
Status Flags                   -- 20
System Cats inc                -- 1
Catalog Partition Number       -- 0
DB Codeset                     -- UTF-8
DB Territory                   -- 
LogID                          -- 1279748926
LogPath                        -- /home/db2inst1/db2inst1/NODE0000/SQL00001/SQLOGDIR/
Backup Buffer Size             -- 524288
Number of Sessions             -- 1
Platform                       -- 12


If the backup was taken online, you can use the db2ckbkp utility with the -l and -o options to identify which logs are required to rollforward the database. Under the LOG.FILE.HEADER section, the "Head Extent ID" line will give you the first log the first log required, and the second number on the "Backup End Marker" will give you the last log required.

BufAddr  PoolID Token Type     Offset   FileSize ObjectSize   OrigSize Object Name
-------- ------ ----- ---- ---------- ---------- ---------- ---------- -----------
00000000:     0     0    8          0      12288      12288          0 "LOG.FILE.HEADER"

          Consistency Counter one = 2245
               Log Format Version = 10
                  Database Log ID = 1279748926
      Number of Primary Log Files = 10
    Number of Secondary Log Files = 2
                    Log File Size = 32
           Transaction Table Size = 128
                          baseLso = 43857761
                       lowtranlsn = 0000000002A431DC
                       minbufflsn = 0000000002A18528
                          headlsn = 0000000002A18528
              hdrSNextExtToRename = 0
                   Head Extent ID = 55
            Last Commit Timestamp = 0  1970-01-01-00.00.00 GMT
                   Last Extent ID = 1280505751
                         Base TID = 00000000038B
                    Database seed = 2690537812
         Log Chain Wrap Indicator = 0
                    rawLogDevSize = 0
                 rawLogHeadExtNum = 0
               Past Log File Size = 32, starting from extent 0
               Past Log File Size = 0, starting from extent 0
               Past Log File Size = 0, starting from extent 0
                    Log File Path = Default
                   Dual Log Flags = 00000000
             Mirror Log File Path = 
                         Last CId = 1280505739
          Soft checkpoint maximum = 131072
                   Log File Flag1 = 00004020
                   Log File Flag2 = 00000000
                   Log File Flag3 = 00000000
                      lfhLogAtBkp = (0, 0, 0)
                     FirstArchNum = 56
                    FirstArchNum2 = SQLPG_EXTNUM_UNDEFINE
                    RenameArchNum = 50
     On-line Backup End Timestamp = 1280505777
           Recoverable Start Time = 1280503612
   Rollforward stoptime in effect = 0
             Backup End Timestamp = 0
                Backup End Marker = 1280505777, 78, 0000000002D0324C


Please refer to the db2ckbkp Information Center link in the 'Related URL' section below to obtain further details on how to use this utility.