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Creating Transaction Logs  



Before a node can perform DECdtm transactions, you must createa transaction log for the node. In an OpenVMS Cluster environment,create a transaction log for each node.
CautionRemoving a node from a cluster after you have createdthe transaction logs can lead to data corruption. For instructionson how to remove a node safely, see Removing a Node.

How to Perform This Task

  1. Foreach node, decide the size and location of the transaction log,using the guidelines in Planning Transaction Logs. Remember that the disks must have enough contiguous spaceto hold the transaction logs.
  2. If you are in a cluster environment,make sure that the disks on which you want to create the transaction logsare mounted clusterwide.
  3. Decide in which directoriesyou want to create the transaction logs. You may want to createnew directories for the transaction logs.
  4. Define SYS$JOURNAL to point to the directories inwhich you want to create the transaction logs: DEFINE/SYSTEM/EXECUTIVE_MODESYS$JOURNAL dirspec[,...]where dirspec is the full specification of a directory in whichyou want to create one or more transaction logs. List all the directoriesthat will contain transaction logs. You can list the directoriesin any order.

    In a cluster environment, use SYSMAN to define SYS$JOURNALclusterwide.
  5. Edit the SYS$MANAGER:SYLOGICALS.COM command procedureto include the SYS$JOURNAL definition.

    If you created node-specific versions of SYLOGICALS.COM, editall the versions.
  6. Create one transaction log for each node, usingLMCP's CREATE LOG command: CREATE LOG [/SIZE=size] dirspecSYSTEM$node.LM$JOURNAL where:

    size
    is the size of the transactionlog in blocks. By default, the size of the transaction log is 4000 blocks.
    dirspec
    is the full specificationof the directory in which you want to create the transaction log.
    node
    is the name of the node.

  7. Make sure DECdtm services are enabled as follows:

    Step Action
    a.
    Check whether the logicalSYS$DECDTM_INHIBIT is defined:
    		$ SHOW LOGICAL SYS$DECDTM_INHIBIT

    b.
    Is SYS$DECDTM_INHIBIT defined?

    Yes DECdtm services are disabled. Enable DECdtm servicesby following the instructions in Disabling DECdtm Services.
    No DECdtm services are enabled.


Example

This example shows how to create transaction logs in an OpenVMSCluster that consists of two nodes whose SCSNODE names are BLUEand RED. Neither node has a node-specific version of SYLOGICALS.COM.

Decide the size and location of the transaction logs:

Node Size of Log (in Blocks) Disk
BLUE
5000
DUA1
RED
4000
DUA2

Mount the disks clusterwide:

$ MOUNT/CLUSTER/SYSTEM DUA1: LOG1$ MOUNT/CLUSTER/SYSTEM DUA2: LOG2
Create directories for the transaction logs:
$ CREATE/DIRECTORY DISK$LOG1:[LOGFILES]$ CREATE/DIRECTORY DISK$LOG2:[LOGFILES]
Define SYS$JOURNAL:
$ RUN SYS$SYSTEM:SYSMANSYSMAN> SET ENVIRONMENT/CLUSTERSYSMAN> DO DEFINE/SYSTEM/EXECUTIVE_MODE SYS$JOURNAL - _SYSMAN> DISK$LOG1:[LOGFILES], DISK$LOG2:[LOGFILES]SYSMAN> EXIT
Edit the SYS$MANAGER:SYLOGICALS.COM command procedure to includethe following line:
$ !$ DEFINE/SYSTEM/EXECUTIVE_MODE SYS$JOURNAL DISK$LOG1:[LOGFILES], -_$DISK$LOG2:[LOGFILES]$ !
Create the transaction logs:
$ RUN SYS$SYSTEM:LMCPLMCP> CREATE LOG/SIZE=5000 DISK$LOG1:[LOGFILES]SYSTEM$BLUE.LM$JOURNALLMCP> CREATE LOG DISK$LOG2:[LOGFILES]SYSTEM$RED.LM$JOURNALLMCP> EXIT
Make sure DECdtm services are enabled:
$ SHOW LOGICAL SYS$DECDTM_INHIBIT%SHOW-S-NOTRAN, no translation for logical name SYS$DECDTM_INHIBIT
SYS$DECDTM_INHIBIT is undefined, so DECdtm services are enabled.
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