Analyze the mount latch contention

The MOUNT LATCH ACTIVITY table shows what user or product is holding the mount latch and what users are waiting for the latch. For example, refer to Figure 1.
Figure 1. Example: MOUNT LATCH ACTIVITY table
SY1  D OMVS,W                                                         
SY1  BPXO063I 12.39.07 DISPLAY OMVS 426                               
OMVS     000E ACTIVE          OMVS=(QY)                               
MOUNT LATCH ACTIVITY:                                                 
    USER   ASID     TCB           REASON                        AGE   
 HOLDER:                                                              
  OMVS     000E  008E9828     Inact Cycle                     00.01.18
     IS DOING: XPFS VfsInactCall / XSYS Message To: SY2               
     FILE SYSTEM: filesystemname.HFS                                  
 WAITER(S):                                                           
  OMVS     000E  008D97C8     FileSys Quiesce                 00.00.05
  OMVS     000E  008E9B58     FileSys Sync                    00.01.10
The key to resolving mount latch contention is in the HOLDER: and IS DOING: fields highlighted in Figure 1.
  • The HOLDER: field tells you what program is holding the mount latch.
  • The IS DOING: field tells you where, in what element or product, the program holding the mount latch is running, and what the program is doing. IS DOING is displayed as IS DOING: activity / [pfs_qualifier]:
    activity
    Description of what the holding task is doing. activity is displayed as one of the following:
    • A wait, such as a latch wait, indicating that the latch holder is waiting for another latch.
    • The type of physical file system (PFS) and the operation that the task was called to do, such as READ, WRITE, MOUNT, or FSYNCH
    pfs_qualifier
    If the activity field shows a PFS, the pfs_qualifier field shows what the PFS is doing. For example, pfs_qualifier might show:
Parent topic: Procedure: Diagnosing and resolving latch contention