IJ02319: ALLOW PCM ALUA CODE TO BE MORE AGGRESSIVE SWITCHING CONTROLLERS APPLIES TO AIX 7100-05

APAR status

• Closed as program error.

Error description

• When using a storage device with preferred and non-preferred
  paths (like IBM Spectrum Virtualize), the AIX default PCM may
  be slow to switch to the non preferred controller when there
  are errors accessing the preferred controller.  For  many
  configurations, the penalty for using the non-preferred
  controller is small, so it would be useful to switch more
  aggressively.
  

Local fix

Problem summary

• When using a storage device with preferred and non-preferred
  paths (like IBM Spectrum Virtualize), the AIX default PCM may
  be slow to switch to the non preferred controller when there
  are errors accessing the preferred controller.  For  many
  configurations, the penalty for using the non-preferred
  controller is small, so it would be useful to switch more
  aggressively.
  

Problem conclusion

• Implemented a new "timeout_policy" for disks.  The new value
  is "fail_ctlr".  If that is set and there is a command time
  out on a path to the perferred controller, and at least one
  other path is either failed or degraded, the PCM will fail all
  paths to the preferred controller, forcing it to use the
  paths to the non preferred controller for future I/O.  The
  PCM only switches back to the preferred controller when there
  is a path that is not failed and not degraded, which will
  take at least 5 times the health check interval.
  
  If the timeout_policy attribute is not changed, or the device
  in use does not have preferred/non-preferred paths, this
  change has no effect.
  

Temporary fix

Comments

• 6100-09 - use AIX APAR IJ02322
  7100-04 - use AIX APAR IJ02455
  7100-05 - use AIX APAR IJ02319
  7200-00 - use AIX APAR IJ02395
  7200-01 - use AIX APAR IJ02390
  7200-02 - use AIX APAR IJ02326
  

APAR Information

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

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

  IJ02322 IJ02326 IJ02379 IJ02390 IJ02395 IJ02455

Fix information

• Fixed component name

  AIX V7.1

• Fixed component ID

  5765H4000

Applicable component levels

• R710 PSY U872323

     UP18/03/06 I 1000