IJ18591: [NFS] GANESHA_STATS FOR SH CHECK SHOWS NO IMPROVEMENT AND FREQU

APAR status

• Closed as program error.

Error description

• The NFS monitor checks the health state of a running NFS
  instance periodically.
  Sometimes the NFS service does not react on some "alive" check
  commands, and that is interpreted as a potential "hung" state.
  Based on the configuration in the mmsysmonitor.conf file either
  a failover or just a warning is triggered then.
  

Local fix

• The behavior or a detected potential "hung" state can be
  customized with the flag  'failoverunresponsivenfs' in the
  mmsysmonitor.conf file,  section [nfs].
  

Problem summary

• Problem description:
  The NFS monitor checks the health state of a running NFS
  instance periodically.
  Sometimes the NFS service does not react on some "alive" check
  commands, and that is interpreted as a potential "hung" state.
  Based on the configuration in the mmsysmonitor.conf file either
  a failover or just a warning is triggered then.
  

Problem conclusion

• Benefits of the solution:
  The fix increases the time span between internal checks up to a
  minute until a decision about a detected "hung" state is made.
  This is much more reliable than the previous approach with
  around 10-20 seconds.
  
  Work Around:
  The behavior or a detected potential "hung" state can be
  customized with the flag  'failoverunresponsivenfs' in the
  mmsysmonitor.conf file,  section [nfs].
  
  The meaning of the flag value is:
  "true" = set an ERROR event (nfs_not_active) if NFS does not
  respond to NULL requests and has no measurable NFS operation
  activity
  
  "false" = set an DEGRADED event (nfs_unresponsive) if NFS does
  not respond to NULL requests and has no measurable NFS operation
  activity
  
  The monitor needs to be restarted after a change
  (mmsysmoncontrol restart).
  The change must be done on all nodes in the same way.
  
  Problem trigger:
  In some cases high I/O load lead to the situation that NFS v3
  and/or v4 NULL requests failed, and that a following internal
  statistics check reported no activity in respect to the number
  of internal NFS operations. These checks are done within a
  timespan of several seconds to a minute. In fact, the system
  might be still functional, and the internally detected
  "unresponsive" state might be just temporarily so that a
  failover would not be advised in this case.
  The monitor interprets the "unresponsiveness"  as a potential
  "hung" state, and triggers either a failover or a warning,
  dependent on the configuration settings.
  
  Symptom: Performance
  Impact/Degradation
  
  Platforms affected:
  ALL Linux OS environments (CES nodes)
  
  Functional Area affected:
  Systemhealth
  
  Customer Impact:
  High Importance
  

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:

  IJ18744

Fix information

• Fixed component name

  SPEC SCALE STD

• Fixed component ID

  5737F33AP

Applicable component levels