IT32602: LONG 'BLOCKED:ARCHIVE' BECAUSE CREATION OF 'USED EXTENT LIST' LACKING READ-AHEAD FOR DBSPACES

APAR status

• Closed as program error.

Error description

• The initial 'Blocked:ARCHIVE' phase of a backup can extend
  siginifcantly depending on the size of the TBLSpace TBLSpace
  partitions in the spaces to be backed up, which in turn usually
  is correlated with the number of tables/fragments/indices in the
  system.  In that phase the backup determines the exact set of
  pages (used extents) that need to go to this particular backup.
  
  This situation seems to be heavily aggravated by the fact that
  all the disk i/o potentially related with this task is done
  direclty, without taking advantage of read-ahead.
  
  Informix versions 12.10.xC14 and onwards prevent this extra disk
  i/o waiting by implementing read-ahead.
  

Local fix

• Pre-populate the bufferpool with required pages shortly before
  starting the backup, by running following stored procedure:
  
  create procedure tblspace_tblspace2bufferpool()
  define i,c int;
  define max_spaceno int;
  let max_spaceno = (select max(dbsnum) from sysdbspaces);
  
   for i in (1 to max_spaceno)
    select count(*) into c
      from syspaghdr pgh, sysptnhdr pth
     where pth.partnum = pgh.pg_partnum
       and pth.partnum = i*1024*1024+1
       and pg_pagenum  < npused;
   end for;
  end procedure;
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Users of Informix Server prior to 12.10.xC14 and 14.10.xC4.  *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Update to Informix Server 12.10.xC14 or 14.10.xC4.           *
  ****************************************************************
  

Problem conclusion

• Fixed in Informix Server 12.10.xC14 and 14.10.xC4.
  

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