Copyright © TIBCO Software Inc. All Rights Reserved
Copyright © TIBCO Software Inc. All Rights Reserved


Chapter 6 Managing Data Sets : Duplexing the Redolog for Recoverability

Duplexing the Redolog for Recoverability
Purpose
A duplex copy of the redolog should be maintained as a safeguard against potential hardware failures experienced while TIBCO Object Service Broker is running.
Creating a Duplex Copy of the Redolog
To create a duplex copy of the redolog follow these steps:
1.
2.
DB TYPE=REDOLOG,DUPLEX=$REDODUP$
The JCL is located in member DBJCL of the JCL data set.
3.
Change the parameter value for the $REDODUP$ OSEMOD symbolic from its default of N to Y.
4.
Change the parameter value for the $REDOVDF$ OSEMOD symbolic from its default of SPLXREDO to DPLXREDO.
These two symbolics are listed in member OSEMOD of the CLIST data set. For more information on customizing OSEMOD symbolics, refer to TIBCO Object Service Broker for z/OS Installing and Operating.
5.
6.
If you want the Data Object Broker to stop processing as the result of an I/O error on either the primary or duplex data set, specify the following Data Object Broker startup parameter:
DUPLEXLOGFAIL=END
The default value is CONTINUE. This instructs the Data Object Broker to continue processing updates as long as there is at least one redolog. For detail information about this and other Data Object Broker parameters, refer to TIBCO Object Service Broker Parameters.
7.
The following gives sample IDCAMS controls cards to allocate a duplex redolog data set:

 
DELETE $HLQVSAM$.$SLQ$.REDOLOG
DELETE $HLQVSAM$.$SLQ$.REDOLOG.DUPLEX
SET MAXCC=0
DEFINE CLUSTER -
(NAME($HLQVSAM$.$SLQ$.REDOLOG) -
UNIQUE BUFSPC(8192) -
VOLUMES($VOLUM05$) -
NONINDEXED -
RECSZ(200,4050) -
CYLINDERS(100,0) CISZ(4096)) -
DATA(NAME(‘$HLQVSAM$.$SLQ$.REDOLOG.DATA’))
DEFINE CLUSTER -
(NAME($HLQVSAM$.$SLQ$.REDOLOG.DUPLEX) -
UNIQUE BUFSPC(8192) -
VOLUMES($VOLUM06$) -
NONINDEXED -
RECSZ(200,4050) -
CYLINDERS(100,0) CISZ(4096)) -
DATA(NAME(‘$HLQVSAM$.$SLQ$.REDOLOG.DATA.DUPLEX’))

 
8.
The S6BTLFRL utility uses the DBDLIB to determine whether the data set is duplexed. If the data set is being duplexed for the first time, the S6BTLFRL utility issues the message S6BLT075E indicating that the primary redolog data set is not empty and that it bypasses formatting it. The duplex redolog data set is dynamically allocated and formatted. The duplex data set for the redolog has the suffix .DUPLEX appended to the name.
For more information about the use of the S6BTLFRL utility, refer to TIBCO Object Service Broker for z/OS Utilities.
9.
10.
The job log should indicate that the redolog data set is duplexed.
Considerations
When the redolog is duplexed, if either the primary or duplex data set is removed, TIBCO Object Service Broker cannot initialize until either the DBGEN is changed or the data set is redefined and reformatted.
During recovery from a redolog data set, TIBCO Object Service Broker automatically recovers from the primary redolog unless an error is detected, in which case recovery switches to the duplex data set. For more information on TIBCO Object Service Broker recovery, refer to Chapter 8, Recovery Procedures.

Copyright © TIBCO Software Inc. All Rights Reserved
Copyright © TIBCO Software Inc. All Rights Reserved