IT42151: COLLECTING BEFORE IMAGES DURING A BACKUP NOT PREPARED FOR BEFOREIMAGE PARTITION REACHING ITS MAXIMUM SIZE

APAR status

• Closed as program error.

Error description

• While a backup is progressing, any pages being modified that
  have not yet gone to the backup will have their before images
  collected in special per-dbspace temp partitions. Should such
  temp partition be unable to grow because of its containing
  dbspace running out of space, a new partition would be allocated
  (in a different dbspace) to accommodate more before images.
  Unfortunately a similar thing does not happen if such partition
  has reached its maximum size (with its home space still offering
  space), and instead before images will be accumulated on an
  in-memory queue, either for the one dbspace the full before
  image partition is associated with or, in case of whole system
  backup, for all dbspaces.
  
  As a consequence a large amount of memory might get allocated
  throughout the remainder of the backup.
  
  Signs for hitting this problem:
  
  a) a line like this in onstat -g arc:
  
  num   DBSpace            Q Size Q Len  Buffer partnum    size
  scanner
  8     dbspace1            2251000 2250931 16     0x2300238
  16777200
  
  with 'size' columns showing a value at or very close to
  16*1024*1024.
  The 'Q Size' value would be an indication of how many more
  before images got queue in memory.
  
  b) an 'archbackup2' thread, in onstat -g ath, showing state
  'terminated' like this:
  
   123772 arcbackup2       11cpu    09/20 02:53:29       66.9910
  3439120    terminated
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Users of Informix Server prior to 12.10.xC16 and 14.10.xC10. *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Informix Server 12.10.xC16 or 14.10.xC10.         *
  ****************************************************************
  

Problem conclusion

• Fixed in Informix Server 12.10.xC16 and 14.10.xC10.
  

Temporary fix

Comments

APAR Information

• 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

  INFORMIX SERVER

• Fixed component ID

  5725A3900

Applicable component levels