IC68858: GENERATE BACKUPSET AND EXPORT PREEMPTION CLARIFICATION.

APAR status

• Closed as program error.

Error description

• GENERATE BACKUPSET and EXPORT commands will be added to the list
  of server processes that are able to preempt a lower priority
  process mountpoint with the following understanding.
  
  Due to APAR IC64494 GENERATE BACKUPSET and EXPORT will only
  preempt to obtain a mountpoint for its output volume.  It is not
  possible for these processes to preempt nor wait for
  availability of a mountpoint for there input volume.  If at the
  time of execution or at any point well these processes are
  running the needed input volume is not available, or there are
  no mountpoint available to allow for the mount of the needed
  input volume then the process will fail.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Tivoli Storage Manager server users of   *
  *                 the GENERATE BACKUPSET or EXPORT command.    *
  ****************************************************************
  * PROBLEM DESCRIPTION: See ERROR DESCRIPTION.                  *
  ****************************************************************
  * RECOMMENDATION: Apply fixing level when available.           *
  *                 This problem is currently projected          *
  *                 to be fixed in levels 5.5.5, 6.1.5,          *
  *                 and 6.2.2. Note that this is subject         *
  *                 to change at the discretion of IBM.          *
  ****************************************************************
  There are two pieces to this problem.  The first piece is a
  code change made by IC64494 to fix a deadlock.  That fix
  caused mount point preemption and waiting for resources to not
  occur anymore.
  
  The second piece of the problem is a code change made in the
  5.4.0.0 version of the Tivoli Storage Manager server.  With
  that change a copy storage pool volume can be selected instead
  of a primary storage pool volume as an input volume for an
  operation if the data to be retrieved from the storage pool
  spans multiple volumes in the primary storage pool but is on a
  single volume in the copy storage pool.  That behavior change
  increased the chance that the deadlock reported by IC64494
  would be encountered.
  
  An undocumented option, IGNORENUMVOLSCHECK, was previously
  added to the Tivoli Storage Manager server to return the
  behavior of this volume selection to what is was before 5.4.0.0.
  

Problem conclusion

• This problem was fixed.
  Affected platforms:  AIX, HP-UX, Sun Solaris, Linux, z/OS, and
  Windows.
  
  The change made for this APAR is to return the waiting for a
  mount point, waiting for a volume, and allowing for preemption
  as was the behavior before the fix for APAR IC64494.  In
  addition to this change, IGNORENUMVOLSCHECK is now also
  enabled by default to help prevent the situation where the
  deadlock reported by IC64494 can occur.
  
  If the user prefers the volume selection to remain as it was
  changed in the 5.4.0.0 level of the Tivoli Storage Manager
  server then IGNORENUMVOLSCHECK NO can be added the the server
  options file to continue to use that new volume selection
  algorithm.
  

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:

  PM20731

Fix information

• Fixed component name

  TSM SERVER

• Fixed component ID

  5698ISMSV

Applicable component levels

• R55A PSY

     UP

• R55H PSY

     UP

• R55L PSY

     UP

• R55S PSY

     UP

• R55W PSY

     UP

• R61A PSY

     UP

• R61H PSY

     UP

• R61L PSY

     UP

• R61S PSY

     UP

• R61W PSY

     UP

• R62A PSY

     UP

• R62H PSY

     UP

• R62L PSY

     UP

• R62S PSY

     UP

• R62W PSY

     UP