IJ46531: DIRECT I/O READ() OR WRITE() SYSTEM CALL FROM/TO LOCAL NSD MAY HANG

APAR status

• Closed as program error.

Error description

• A read() or write() system call on a file descriptor opened in
  direct I/O mode accessing file data on a locally attached NSD
  may hang.
  

Local fix

• Do not use direct I/O for data stored on locally attached NSDs.
  Or use direct I/O only on remote attached NSDs.
  

Problem summary

• A read() or write() system call on a file descriptor opened in
  direct I/O mode accessing file data on a locally attached NSD
  may hang.
  

Problem conclusion

• This problem is fixed in 5.1.2.11
  To see all Spectrum Scale APARs and their respective
  Fix solutions refer to page:
  https://public.dhe.ibm.com/storage/spectrumscale/spectrum_scale_
  apars.html
  
  Benefits of the solution:
  A read() or write() system call meeting above requirements will
  not longer hang and a proper error recovery will be initiated.
  
  Work Around:
  Do not use direct I/O for data stored on locally attached NSDs.
  Or use direct I/O only on remote attached NSDs.
  
  Problem trigger:
  When preparing the block I/O request to the local attached block
  device the GPFS kernel module is unable to get a handle for the
  block device. This can for example happen if the block device is
  temporarily unavailable.
  
  Symptom:
  Hang/Deadlock/Unresponsiveness/Long Waiters
  
  Platforms affected:
  ALL Linux OS environments
  
  Functional Area affected:
  NSD Client/Server handling
  
  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:

Fix information

• Fixed component name

  SPEC SCALE STD

• Fixed component ID

  5737F33AP

Applicable component levels