IJ45608: OFFLINE FSCK MMFSCK CAN REPORT FALSE POSITIVE LOST BLOCKS AND ALSO NOT REPORT PROPERLY GENUINE INCORRECT BLOCKS AND DUPLICATES

APAR status

• Closed as program error.

Error description

• Due to an issue identified in offline fsck mmfsck it can cause
  it to report false positive lost blocks and also not report
  properly genuine incorrect blocks and duplicates.
  

Local fix

• 1) Create one or more "dummy" dataOnly pool by adding a single
  NSD of that "dummy" dataOnly pool to the file system. The NSD of
   this "dummy" data pool can be of a minimum small size as we do
  not need to have any data on that "dummy" data pool.
  
  2) After that run offline fsck on the file system and now it
  should report and repair lost blocks/incorrect block and
  duplicates in the right way.
  
  3) Once the file system is fixed you can delete the "dummy" data
   pool by deleting the only NSD in it.
  

Problem summary

• Due to an issue identified in offline fsck mmfsck it can cause
  it to report false positive lost blocks and also not report
  properly genuine incorrect blocks and duplicates.
  

Problem conclusion

• This problem is fixed in 5.1.2.10
  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:
  
  Offline fsck mmfsck will be able to detect and fix corruptions
  of lost blocks, incorrect blocks and duplicates properly.
  
  Work Around:
  1) Create one or more "dummy" dataOnly pool by adding a single
  NSD of that "dummy" dataOnly pool to the file system. The NSD of
   this "dummy" data pool can be of a minimum small size as we do
  not need to have any data on that "dummy" data pool.
  2) After that run offline fsck on the file system and now it
  should report and repair lost blocks/incorrect block and
  duplicates in the right way.
  3) Once the file system is fixed you can delete the "dummy" data
   pool by deleting the only NSD in it.
  
  Problem trigger:
   This issue will happen on a file system where the user created
  two or more dataOnly pools and then at some point of time
  deleted the earlier data pool/s in an out of order fashion (i.e.
   a dataonly pool (n) is deleted with other data pools (n+x) are
  present).
  
  Symptom:
  Will see corruptions like duplicates even after offline fsck
  repair and subsequent offline fsck runs will show lost blocks
  and incorrect blocks.
  
  Platforms affected:
  ALL Operating System environments
  
  Functional Area affected:
  FSCK
  
  Customer Impact:
  Critical
  

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:

  IJ45609

Fix information

• Fixed component name

  SPEC SCALE STD

• Fixed component ID

  5737F33AP

Applicable component levels