OA61014: ZFS SPACE USED GROWING. UNNECESSARY DYNAMIC EXTENSIONS. 21/03/16 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• There is a possiblility of zFS space not being freed properly
  after a file is removed, yet remains open by another process on
  the system. The zero link count (zlc) processing is not cleaning
  up deleted files and freeing the space in all cases.
  This may result in unnecessary extends in extreme cases.
  This problem is specific to RWSHARE file systems and limited to
  such
  
  PE INFORMATION:
  USERS AFFECTED:
  All zOS 2.3 and 2.4 zFS. After application of
  OA57508 ptfs UJ01635 or UJ01636
  
  USER IMPACT:
  Possible unnecessary dynamic extensions / grows of the zFS file
  system. Possible un-reclaimed space until the file system is
  unmounted and remounted.
  RECOMMENDATION:IBM recommendation is to not back out the
  maintenance. There are several fixes in this stream that resolve
  more other, more severe issues. This issue is limited in scope
  to RWSHARE.
  ANALYSIS:
  zlc processing is not cleaning up files properly at times
  
  KNOWN IMPACT:
  Used space in an RWSHARE file system may creep up, even though
  no new significant change to the contents.
  
  VERIFICATION STEPS:
  zfsadm fsinfo  can be used to confirm the number of file system
  objects, as well as 8k blocks free
  
  ADDITIONAL SYMPTOMS:
  IOEZ00312I
  IOEZ00078E
  IOEZ00853I
  

Local fix

• BYPASS/CIRCUMVENTION:
  Unmount and remount the file system
  Switch mount mode from RW to RO and back to RW
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * zFS Version 2 Release 3                                      *
  * zFS FMID:HZFS430                                             *
  *                                                              *
  * zFS Version 2 Release 4                                      *
  * zFS FMID:HZFS440                                             *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * In a sysplex environment, fsinfo and                         *
  * df statistics showed a space increase                        *
  * condition against an active RWSHARE                          *
  * zfs file system. Over time the file                          *
  * system could become full due to                              *
  * the  growing number of file system                           *
  * objects and result in an ENOSPC                              *
  * condition. Following an IPL and                              *
  * a file system ownership move,                                *
  * the space condition was resolved and                         *
  * the number of  file system objects                           *
  * returned to a lower value.                                   *
  *                                                              *
  * After the activation of OA57508                              *
  * (HZFS430 UJ01635 or HZFS440                                  *
  * UJ01635), the reported issue can be                          *
  * observed. APAR OA57508 added new                             *
  * function,  however it prevented                              *
  * zlc processing from cleaning up file                         *
  * system objects no longer needed. This                        *
  * caused the storage growth condition                          *
  * against the zfs file system.                                 *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Code added in the new function provided in OA57508
  caused a regression in zlc(zero link count) processing.This
  prevented file system objects to be considered for deletion.
  During cleanup processing, since these file system objects
  were not flagged, they are left allocated causing the storage
  growth.
  

Problem conclusion

• A fix was added in get_opendelete to set a zlc init reset flag
  to ensure zlc/cleanup processing would delete these system
  objects preventing storage growth condition.
  

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:

  UJ05275

Modules/Macros

• IOEFSKN
  

Fix information

• Fixed component name

  ZFS ZSERIES FIL

• Fixed component ID

  5696EFS00

Applicable component levels

• R430 PSY UJ05136

     UP21/05/04 P F105 {

• R440 PSY UJ05137

     UP21/04/30 P F104 {

Fix is available

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