RESERVES

The RESERVES (RES) service helps determine the cause of poor DASD performance or system lockouts.

It also

  • displays reserve activity for DASD devices

  • displays system contention caused by long-term reserves

    A reserve issued by one processor for a single resource prevents all other processors from accessing the entire volume.

Note

To prevent reserve information for specific volumes from displaying, add the VOLSER to BBPARM member $$XRES. See XRES.

Syntax

GUID-E994AC74-F678-41D6-8DD0-7F4F6EE13C10-low.png

Example

To display reserve activity on DASD devices, type

RESERVES

          [1]     [2]     [3]         [4]
AMTQ2PI SYSTEM  (LOCAL) Q=PINION    R=BAB301
AMTQ2QI SYSID  JOBNAME   ASID   STAT TYP TIME 15:01:14
         [5]    [6]      [7]    [8]  [9] [10]    [11] [12]
AMTQ2RI SJSD   VAM3RES  (0057)  OWNS EXC RES=001      877B BAB301
AMTQ1LI

Legend:

  1. scope of enqueue; possible scopes are as follows:
    • SYSTEMS
    • SYSTEM
    • STEP
  2. whether the resource is global or local
  3. major name (Q=)
  4. minor name (R=)
  5. system ID for the system executing the task that is holding or waiting for the resource

  6. job name, TSO user ID, or Started-Task ID for the address space containing the task that is holding or waiting for the resource

    The job name is not available in some situations.

  7. ID for the address space holding or waiting for the resource
  8. current status (OWNS or WAIT), indicating that the task holds (OWNS) the resource or is waiting (WAIT) for the resource
  9. type of enqueue: EXC for exclusive, SHR for shared
  10. reserve information
    • RES indicates that a reserve is associated with the enqueue. The reserve count is also displayed unless it is zero, in which case the equal sign is also omitted.
    • CVT indicates that reserve request has been converted to global enqueue. The remaining four fields may not appear.

  11. if present, indicates that the reserve is pending, which means that the task is waiting to reserve the devices

    Generally, the device is reserved by another system.

  12. device address in hexadecimal format

Related topic

Services

 

Tip: For faster searching, add an asterisk to the end of your partial query. Example: cert*