IT26239: KERNEL HANGS SEEN IN VSNAP

Download Information: Version 10.1.2.x IBM Spectrum Protectâ„¢ Plus

APAR status

• Closed as program error.

Error description

• When a vSnap server is under high load, "task blocked for more
  than 120 seconds" appears in the vSnap syslog:
  
  Jul 28 21:55:01 vsnap.host.name: INFO: task z_zvol:21063 blocked
  for more than 120 seconds.
  Jul 28 21:55:01 vsnap.host.name: "echo 0 >
  /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  
  These messages should be interpreted as warnings when there is
  significant IO load that may lead to slow disk writes.
  
  IBM Spectrum Protect Versions Affected:
  IBM Spectrum Protect Plus 10.1.0 and 10.1.1
  
  Customer/L2 Diagnostics
  
  Initial Impact: Low
  
  Additional Keywords: SPP, SPplus, TS001195656
  

Local fix

• Enable the "Synchronous Write" option within the SPP UI. Go to
  the Backup Storage page and click on the Manage icon for a
  particular vSnap. You will find the option alongside the
  compression and dedup options.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * IBM Spectrum Protect Plus levels 10.1.1.*                    *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See ERROR DESCRIPTION                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * This has been fixed in level 10.1.2.                         *
  * Note that this is subject to change at the discretion of IBM *
  ****************************************************************
  

Problem conclusion

• During significant I/O operations within vSnap disk writes may
  slow down and reveal "task blocked for more than 120 seconds"
  messages within the vSnap syslog. vSnap has been enhanced to
  increase the task timeout to minimize the occurences of these
  messages.
  

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:

Modules/Macros

•    VSNAP
  

Fix information

• Fixed component name

  SP PLUS

• Fixed component ID

  5737SPLUS

Applicable component levels