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IT27443: HIGH MEMORY CONSUPTION WITH CDC IF BACKUPS WITH MULTIPLE SEQUENCES(TARGET LOCATIONS)

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APAR status

  • Closed as program error.

Error description

  • User found the memory of process db2sysc kept increasing,and
    until run out of system memory,they must rebooting machine to
    free it.
    The symptom is the total size of pool dbheap kept increasing
    quickly when enabling CDC replication.
    
    $db2pd -memblocks sort -alldbp
    
    Memory blocks sorted by size for dbh pool: (PoolID: 2, SecondID:
    0, PoolAddr: 0x0A000200000004B0)
    PoolID     PoolName   TotalSize(Bytes)     TotalCount LOC   File
    
    2          dbh        15382967040          42730464   1541
    1615387857
    
    This problem affects users of readlog API and also affect the
    RECOVERY command.
    
    You can use LIST HISTORY to check whether your backup pointed to
    mutiple sequences:
    
    $ db2 backup db sample to
    /home/backup/dir1,/home/backup/dir2,/home/backup/dir3
    
    Backup successful. The timestamp for this backup image is :
    20181218213458
    
    $ db2 list history backup all for db sample
    
                        List History File for sample
    
    Number of matching file entries = 3
    
    
     Op Obj Timestamp+Sequence Type Dev Earliest Log Current Log
    Backup ID
     -- --- ------------------ ---- --- ------------ ------------
    --------------
      B  D  20181218213458001   F    D  S0000000.LOG S0000000.LOG
    
    ----------------------------------------------------------------
    ------------
      Contains 5 tablespace(s):
    
     00001 SYSCATSPACE
     00002 USERSPACE1
     00003 IBMDB2SAMPLEREL
     00004 IBMDB2SAMPLEXML
     00005 SYSTOOLSPACE
    
    ----------------------------------------------------------------
    ------------
        Comment: DB2 BACKUP SAMPLE OFFLINE
     Start Time: 20181218213458
       End Time: 20181218213503
         Status: A
    
    ----------------------------------------------------------------
    ------------
      EID: 4 Location: /home/backup/dir1
    
    
     Op Obj Timestamp+Sequence Type Dev Earliest Log Current Log
    Backup ID
     -- --- ------------------ ---- --- ------------ ------------
    --------------
      B  D  20181218213458002   F    D  S0000000.LOG S0000000.LOG
    
    ----------------------------------------------------------------
    ------------
      Contains 5 tablespace(s):
    
     00001 SYSCATSPACE
     00002 USERSPACE1
     00003 IBMDB2SAMPLEREL
     00004 IBMDB2SAMPLEXML
     00005 SYSTOOLSPACE
    
    ----------------------------------------------------------------
    ------------
        Comment: DB2 BACKUP SAMPLE OFFLINE
     Start Time: 20181218213458
       End Time: 20181218213503
         Status: A
    
    ----------------------------------------------------------------
    ------------
      EID: 5 Location: /home/backup/dir2
    
    
     Op Obj Timestamp+Sequence Type Dev Earliest Log Current Log
    Backup ID
     -- --- ------------------ ---- --- ------------ ------------
    --------------
      B  D  20181218213458003   F    D  S0000000.LOG S0000000.LOG
    
    ----------------------------------------------------------------
    ------------
      Contains 5 tablespace(s):
    
     00001 SYSCATSPACE
     00002 USERSPACE1
     00003 IBMDB2SAMPLEREL
     00004 IBMDB2SAMPLEXML
     00005 SYSTOOLSPACE
    
    ----------------------------------------------------------------
    ------------
        Comment: DB2 BACKUP SAMPLE OFFLINE
     Start Time: 20181218213458
       End Time: 20181218213503
         Status: A
    
    ----------------------------------------------------------------
    ------------
      EID: 6 Location: /home/backup/dir3
    

Local fix

  • Prune the history file and only take backups with 1 target
    location.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1 Mod 4 Fixpack 5 or higher                *
    ****************************************************************
    

Problem conclusion

  • First fixed in Db2 11.1 Mod 4 Fixpack 5
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT27443

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-12-19

  • Closed date

    2020-01-16

  • Last modified date

    2020-01-16

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB10 PSN

       UP

[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"Business Unit":{"code":"BU053","label":"Cloud \u0026 Data Platform"},"Product":{"code":"SSEPGG","label":"DB2 for Linux- UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1"}]

Document Information

Modified date:
02 September 2021