Analyze the file latch contention

The FILE LATCH ACTIVITY table shows what user or product is holding the file latch and what users are waiting for the latch. For example, refer to Figure 1.
Figure 1. Example: FILE LATCH ACTIVITY table
FILE LATCH ACTIVITY:                                                  
    USER   ASID     TCB             SHR/EXCL                    AGE   
----------------------------------------------------------------------
LATCH  14  LSET 01  TYPE REGFILE   DEVNO 2 INO 204        
FILE: myfile
FILE SYSTEM: ZOS112.ETC.ZFS
 HOLDER(S):                                                           
  TCO   0026      008E6D90           EXCL                    00.00.56
     TIME: 2010/10/08 16.21.36                                       
     IS DOING: ZFS MKDirCall                                                  
 WAITER(S):   
  TCO  0027       008E6D90           SHR                     00.06.51
     TIME:  2010/10/08  16.21.38                                       
                      .
                      .
                      .
The key to resolving file latch contention is in the HOLDER: and IS DOING: fields highlighted in tFigure 1.
  • The HOLDER: field tells you what program is holding the file latch.
  • The IS DOING: field tells you where, in what element or product, the program holding the file latch is running, and what the program is doing. First, we'll decode field 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 either:
    • A wait, such as a file 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