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Enabling DECdtm Services  



Enable DECdtm services only if you have previously disabledthem and you now want to run software that uses DECdtm services.

How to Perform This Task

  1. Deassign thelogical name SYS$DECDTM_INHIBIT:
    $ DEASSIGN/SYSTEM/EXECUTIVE_MODE SYS$DECDTM_INHIBIT
    In an OpenVMS Cluster, use SYSMAN to deassign SYS$DECDTM_INHIBITclusterwide.
  2. Start up the DECdtm services process, TP_SERVER:
    $ @SYS$STARTUP:DECDTM$STARTUP.COM
    In an OpenVMS Cluster, use SYSMAN to start up the TP_SERVERprocess clusterwide.
  3. Edit the SYS$MANAGER:SYLOGICALS.COM command procedureto delete the SYS$DECDTM_INHIBIT definition. This ensures that DECdtmservices start automatically when you boot the system.

Example

This example shows how to enable DECdtm services in a clusterenvironment.

Deassign SYS$DECDTM_INHIBIT, then start up the TP_SERVER process.

$ RUN SYS$SYSTEM:SYSMANSYSMAN> SET ENVIRONMENT/CLUSTERSYSMAN> DO DEASSIGN/SYSTEM/EXECUTIVE_MODE SYS$DECDTM_INHIBITSYSMAN> DO @SYS$STARTUP.DECDTM$STARTUP.COMSYSMAN> EXIT
Edit the SYS$MANAGER:SYLOGICALS.COM command procedure to delete the SYS$DECDTM_INHIBIT definition.

Restrictions

DECdtm induces a system critical failure (BUGCHECK), whichleads to a crash, when it does not have the operating environmentit requires to perform its tasks. A typical example is the failureto allocate virtual memory. Such errors are treated as serious exceptionsto DECdtm and hence fail with a BUGCHECK, which eventually crashesthe system.

DECdtm depends mainly on its data structures to maintain theintegrity and consistency of its transactions. Hence, any erroror fatal condition during its execution is treated as a seriousdiscrepancy; therefore, DECdtm raises a fatal exception and crashesthe system.

HP recommends that you ensure that the operating environmenthas sufficient buffer in its system resources such as virtual memoryand non-paged pool. If the crash occurs in an environment whereDECdtm is not used, HP recommends that you prevent DECdtm from startingup. (To prevent DECdtm from starting up, refer to the section Disabling DECdtm Services.)

Defining a DECdtm Logical to Handle "InsufficientDynamic Memory" on I64 Platforms

A DECdtm logical is provided to handle insufficient dynamicmemory that occurs during the allocation of memory for the KPB (KernelProcess Block). The design logic is called Retry Logic; it allowsusers to define the system table logical name SYS$DECDTM_KPBALLOC_RETRYCNTto configure for the number of times (the Retry Count) the callto the system service EXE$KP_ALLOCATE_KPB is to be repeated whenthe return code is SS$_INSFMEM.

The system logical SYS$DECDTM_KPBALLOC_RETRYCNT is equatedto the option string literal "MIN", "DEF",or "MAX." The string literals indicate a retrycount of MIN=25, DEF=50, and MAX=100.

If the logical name SYS$DECDTM_KPBALLOC_RETRYCNT is not foundin the system table, then the default count of DEF=50 is used forthe Retry Logic.

Example:

$ DEFINE/SYS/EXEC SYS$DECDTM_KPBALLOC_RETRYCNT MAX


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