OA66647: UNMOUNT HANG DUB WAIT IN AUTOMOUNT FOR MOUNT CATCHUP AFTER PTF FOR OA62734 24/07/25 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Customer installed PTF for OA62734 and experienced hung
  unmount requests, as well as jobs hanging in automount during
  dub processing waiting for mount catchup to occur.
  The 'F BPXOINIT,FILESYS=D' display shows that UNMOUNT
  processing has been hung on a system for a long period of time.
  For example:
  -
  SYSTEMS PERFORMING UNMOUNT
  (Since 2024/06/18 11.31.33)
  NUMBER OF UNMOUNTS IN PROGRESS=       1
  SY1
  
  
  ANALYSIS:
  The PTFs (UJ94644, UJ94645) for APAR OA62734 introduced a timing
  
  
  
  window in unmount processing. BPXFSUMT sets bits VfsUmountReq
  and VfsNsUmountReq, but if BPXFTCLN runs in the window, it can
  turn off the VfsUmountReq flag that BPXFSUMT just set.  This
  unexpected state leads to a file system being left indefinitely
  hung in unmount processing.
  
  
  KNOWN IMPACT:
  This hung unmount request holds up other serialized shared
  file system activity, including mount catchup (resync), move,
  initialization, file system takeover processing, and additional
  unmount requests.
  
  
  VERIFICATION STEPS:
  1.) Verify that PTF for OA62734 is installed in a shared file
     system environment.
  2.) From 'F BPXOINIT,FILEYS=D' display, verify that a system has
  
    been stuck performing UNMOUNT processing for an excessive
    amount of time.
    NOTE: the number of unmounts in progress should be 1.
  3.) Find the file system that is stuck unmounting via the
    'F BPXOINIT,FILESYS=D,EXCEPTION' output.  Specifically, you
    are looking for a file system with a STATUS of 'UNMOUNT IN
    PROGRESS'.
  
  
  ADDITIONAL SYMPTOMS:
  MSGBPXF076I FILE SYSTEM INITIALIZATION IS DELAYED DUE TO
  CONFLICTING ACTIVITY ON ANOTHER SYSTEM
  BPXF076I
  
  MSGBPXF217E FILE SYSTEM PARTITION CLEANUP FAILED DUE TO UNMOUNT
  PROCESSING ON SYSTEM ssss
  BPXF217E
  
  ABENDEC6 RSN127C0793 MemberGoneDelay
  
  
  PE INFORMATION:
  USERS AFFECTED:
  Users with APAR OA62734 installed:
  Users at release z/OS V2R5 (HBB77D0) with PTF UJ94645
  installed.  Users at release z/OS 3.1 (HBB77E0)  with PTF
  UJ94644 installed.
  
  Users with APAR OA66101 installed:
  Users at release z/OS V2R5 (HBB77D0) with PTF UJ94946
  installed.  Users at release z/OS 3.1 (HBB77E0)  with PTF
  UJ94940 installed.
  
  Users with APAR OA66213 installed:
  Users at release z/OS V2R5 (HBB77D0) with PTF UJ95437
  installed.  Users at release z/OS 3.1 (HBB77E0)  with PTF
  UJ95430 installed.
  
  USER IMPACT:
  APAR OA62734 introduced mount namespace functionality in
  support of z/OS Container Platform.  The changes made via this
  APAR introduced a timing window in unmount processing that can
  lead to an unmount hang in a shared file system sysplex,
  causing other shared file system serialized activity to backup,
  including mount catchup (resync), move, initialization, file
  system takeover processing, and additional unmount requests.
  APAR OA66101 is based off of OA62734. It fixes various
  failures in the mount namespace related functions.
  APAR OA66213 is also based off of OA62734. It fixes various
  failures when using mount namespaces or union file system.
  USS-2360 has HIPER symptom. A rare scenario can occur when
  using union file system, causing dead lock in the system.
  The recommendation is to restore the PTF for OA62734.
  
  
  ZOSCP/K
  

Local fix

• RECOVERY ACTION:
  An IPL of the system performing the unmount can likely be
  avoided by issuing 'F BPXOINIT,FILESYS=D,EXCEPTION' to look for
  where the OMVS CDS reflects a STATUS of 'UNMOUNT IN PROGRESS'.
  For example:
  
  SY1.USER1.ZFS                                23063  RDWR
  PATH=/u/user1
  STATUS=UNMOUNT IN PROGRESS    LOCAL STATUS=ACTIVE
  OWNER=SY1         RECOVERY OWNER=SY1      AUTOMOVE=Y PFSMOVE=Y
  TYPENAME=ZFS      MOUNTPOINT DEVICE=      46
  MOUNTPOINT FILESYSTEM=*AMD/u
  ENTRY FLAGS=90471400  FLAGS=40000000  LFSFLAGS=00000002
  LOCAL FLAGS=40000002  LOCAL LFSFLAGS=00000002
  ACTIVECHK  =00000000  LFSFLAGS2     =D0003400
  *STATUS AND LOCAL STATUS ARE INCONSISTENT
  
  To unmount it, issue
  'F BPXOINIT,FILESYS=UNMOUNT,FILESYSTEM=SY1.USER1.ZFS'.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of z/OS UNIX System Services in                    *
  * a shared file system environment for                         *
  * HBB77D0 and HBB77E0 with OA62734 installed.                  *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * A hung unmount prevents other mutually                       *
  * exclusive file system events from                            *
  * occurring.                                                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A timing window was encountered while two unmounts were
  processing and the unmount flag was mistakenly turned off in
  the file system control block. With the unmount flag turned off,
  the unmount was aborted and did not get cleaned up.
  

Problem conclusion

• BPXFTCLN is changed (via NsmtCheckForUnmount) to not turn off
  VfsUmountReq when VfsNsUmountReq is not on. That code is no
  longer necessary as namespace termination unmounts are
  serialized and performed only by BPXFTCLN.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UJ95690 UJ95699

Modules/Macros

• BPXFTCLN
  

Fix information

• Fixed component name

  OPENMVS SYS SRV

• Fixed component ID

  5695SCPX1

Applicable component levels

• R7E0 PSY UJ95690

     UP24/08/07 P F408 ­

• R7D0 PSY UJ95699

     UP24/08/07 P F408 ­

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.