This topic provides tips for using the more common options for journal definitions. Context-sensitive help is available online for all options on the journal definition commands.
Journal definition (JRNDFN) This parameter is a two-part name that identifies a journaling environment on a system. The first part of the name identifies the journal definition. The second part of the name identifies a system definition which represents the system on which you want the journal to reside.
Journal definitions created by other MIMIX configuration operations may assign specific names for the first part of the name. See Journal definition naming conventions.
Journal (JRN) This parameter specifies the qualified name of a journal to which changes to files or objects to be replicated are journaled. For the journal name, the default value *JRNDFN uses the name of the journal definition for the name of the journal.
For the journal library, the default value *DFT allows MIMIX to determine the library name based on the ASP in which the journal library is allocated, as specified in the Journal library ASP parameter. If that parameter specifies *ASPDEV, MIMIX uses #MXJRNIASP for the default journal library name; otherwise, the default library name is #MXJRN.
Journal library ASP (JRNLIBASP) This parameter specifies the auxiliary storage pool (ASP) from which the system allocates storage for the journal library. You can use the default value *CRTDFT or you can specify the number of an ASP in the range 1 through 32.
The value *CRTDFT indicates that the command default value for the IBM i Create Library (CRTLIB) command is used to determine the auxiliary storage pool (ASP) from which the system allocates storage for the library.
For libraries that are created in a user ASP, all objects in the library must be in the same ASP as the library.
Journal receiver prefix (JRNRCVPFX) This parameter specifies the prefix to be used in the name of journal receivers associated with the journal used in the replication process and the library in which the journal receivers are located.
The prefix must be unique to the journal definition and cannot end in a numeric character. The default value *GEN for the name prefix indicates that MIMIX will generate a unique prefix, which usually is the first six characters of the journal definition name with any trailing numeric characters removed. If that prefix is already used in another journal definition, a unique six character prefix name is derived from the definition name. If the journal definition will be used in a configuration which broadcasts data to multiple systems, there are additional considerations. See Journal definition considerations.
The value *DFT for the journal receiver library allows MIMIX to determine the library name based on the ASP in which the journal receiver is allocated, as specified in the Journal receiver library ASP parameter. If that parameter specifies *ASPDEV, MIMIX uses #MXJRNIASP for the default journal receiver library name. Otherwise, the default library name is #MXJRN. You can specify a different name or specify the value *JRNLIB to use the same library that is used for the associated journal.
Journal receiver library ASP (RCVLIBASP) This parameter specifies the auxiliary storage pool (ASP) from which the system allocates storage for the journal receiver library. You can use the default value *CRTDFT or you can specify the number of an ASP in the range 1 through 32.
The value *CRTDFT indicates that the command default value for the IBM i Create Library (CRTLIB) command is used to determine the auxiliary storage pool (ASP) from which the system allocates storage for the library.
For libraries that are created in a user ASP, all objects in the library must be in the same ASP as the library.
Target journal state (TGTSTATE) This parameter specifies the requested status of the target journal, and can be used with active journaling support or journal standby state. Use the default value *ACTIVE to set the target journal state to active when the data group associated with the journal definition is journaling on the target system (JRNTGT(*YES)). Use the value *STANDBY to journal objects on the target system while preventing most journal entries from being deposited into the target journal.
Target journal inspection (TGTJRNINSP) This parameter specifies whether to enable target journal inspection on the specified journal. The shipped default value, *YES, allows the journal to be inspected when the system identified in the journal definition is the target system for data group replication. Target journal inspection checks the specified journal for changes to replicated objects that were initiated on the target system by users or processes other than MIMIX and reports the activity.
When *YES is specified and the specified journal is a user journal, the value *ACTIVE must be specified for the Target journal state (TGTSTATE). (The IBM feature for High Availability Journal Performance is not required.) Also, any data groups definitions using this journal definition must allow the data groups to journal on the target system.
Because inspection occurs at the journal level on a system, enabling inspection for a system journal (QAUDJRN) affects all data groups using the system identified in the journal definition as their target system. Similarly, enabling inspection for a user journal affects any data groups using the journal definition as their target system.
Journal caching (JRNCACHE) This parameter specifies whether the system should cache journal entries in main storage before writing them to disk. This option is only available if a separately chargeable feature from IBM (Option 42) is available on the system. The default value, *NONE, prevents unintentional use of this feature. The value *BOTH results in journal caching on both the source and the target systems. You can also specify values *SRC or *TGT to perform journal caching on only the source or target system.
Receiver change management (CHGMGT, THRESHOLD, TIME, RESETTHLD2 or RESETTHLD) Several parameters control how journal receivers associated with the replication process are changed.
The Receiver change management (CHGMGT) parameter controls whether MIMIX performs change management operations for the journal receivers used in the replication process. The shipped default value of *TIMESIZE results in MIMIX changing journal receivers by both threshold size and time of day.
The following parameters specify conditions that must be met before change management can occur.
-
Receiver threshold size (MB) (THRESHOLD) You can specify the size, in megabytes, of the journal receiver at which it is changed. The default value is 6600 MB. This value is used when MIMIX or the system changes the receivers.
If you decide to decrease the size of the Receiver threshold size you will need to manually change your journal receiver to reflect this change.
If you change the journal receiver threshold size in the journal definition, the change is effective with the next receiver change.
-
Time of day to change receiver (TIME) You can specify the time of day at which MIMIX changes the journal receiver. The time is based on a 24 hour clock and must be specified in HHMMSS format.
-
Reset large sequence threshold (RESETTHLD2) You can specify the sequence number (in millions) at which to reset the receiver sequence number. When the threshold is reached, the next receiver change resets the sequence number to 1.
For information about how change management occurs in a remote journal environment and about using other change management choices, see Journal receiver management
Receiver delete management (DLTMGT, KEEPUNSAV, KEEPRCVCNT, KEEPJRNRCV) Four parameters control how MIMIX handles deleting the journal receivers associated with the replication process.
The Receiver delete management (DLTMGT) parameter specifies whether or not MIMIX performs delete management for the journal receivers. By default, MIMIX performs the delete management operations. MIMIX operations can be adversely affected if you allow the system or another process to handle delete management. For example, if another process deletes a journal receiver before MIMIX is finished with it, replication can be adversely affected.
All of the requirements that you specify in the following parameters must be met before MIMIX deletes a journal receiver:
-
Keep unsaved journal receivers (KEEPUNSAV) You can specify whether or not to have MIMIX retain any unsaved journal receivers. Retaining unsaved receivers allows you to back out (rollback) changes in the event that you need to recover from a disaster. The default value *YES causes MIMIX to keep unsaved journal receivers until they are saved.
-
Keep journal receiver count (KEEPRCVCNT) You can specify the number of detached journal receivers to retain before the receivers are considered eligible for deletion and reported as extra receivers. For example, if you specify 2 and there are 10 journal receivers including the attached receiver (which is number 10), MIMIX retains two detached receivers (8 and 9).
-
Keep journal receivers (days) (KEEPJRNRCV) You can specify the number of days to retain detached journal receivers before the receivers are considered eligible for deletion and reported as extra receivers. This parameter is based on the date when a journal receiver was detached, not on a 24 hour cycle. A receiver is eligible for deletion after the specified number of days have passed from the time it became detached. The exact time of the deletion may vary based on the configuration of the journal manager.
For information see Journal receiver management
Journal receiver ASP (JRNRCVASP) This parameter specifies the auxiliary storage pool (ASP) from which the system allocates storage for the journal receivers. The default value *LIBASP indicates that the storage space for the journal receivers is allocated from the same ASP that is used for the journal receiver library.
Threshold message queue (MSGQ) This parameter specifies the qualified name of the threshold message queue to which the system sends journal-related messages such as threshold messages. The default value *JRNDFN for the queue name indicates that the message queue uses the same name as the journal definition. The value *JRNLIB for the library name indicates that the message queue uses the library for the associated journal.
Exit program (EXITPGM) This parameter allows you to specify the qualified name of an exit program to use when journal receiver management is performed by MIMIX. The exit program will be called when a journal receiver is changed or deleted by the MIMIX journal manager. For example, you might want to use an exit program to save journal receivers as soon as MIMIX finishes with them so that they can be removed from the system immediately.
Receiver size option (RCVSIZOPT) This parameter specifies what option to use for determining the maximum size of sequence numbers in journal entries written to the attached journal receiver. Changing this value requires that you change to a new journal receiver. In order for a change to take effect the journaling environment must be built. When the value *MAXOPT3 is used, the journal receivers cannot be saved and restored to systems with operating system releases earlier than V5R3M0.
To support a switchable data group, a change to this parameter requires more than one journal definition to be changed. For additional information, see Changing the journaling environment to use *MAXOPT3
Minimize entry specific data (MINENTDTA) This parameter specifies which object types allow journal entries to have minimized entry-specific data. For additional information about improving journaling performance with this capability, see Minimized journal entry data.
Reset sequence threshold (RESETTHLD) You can specify the sequence number (in millions) at which to reset the receiver sequence number. When the threshold is reached, the next receiver change resets the sequence number to 1. You can specify a value for this parameter or for the RESETTHLD2 parameter, but not both. RESETTHLD2 is recommended.