The scope and uniqueness of Db2 subsystem parameters in data sharing
Although various parameters affect the operation of only a single member, some parameters must have the same value on all the members. For example, each catalog alias name must be the same. Other parameter values must be different on each member. For example, each member specifies a different BSDS name.
The values of most parameters do not need to be unique. Recommendations are offered for some of these parameters. In the following tables, the parameter is indicated by the name of the corresponding installation panel field. However, some of the parameters do not reside in the DSNZPxxx load module.
Parameter values that must be different on each member
The list below shows the values of the installation panel fields that must be different for every member of a data sharing group. You specify values for these fields when a member is installed, migrated, or updated.
- Active Logs: COPY 1 PREFIX
- Active Logs: COPY 2 PREFIX
- Archive Logs: COPY 1 PREFIX (ARCPFX1 parameter)
- Archive Logs: COPY 2 PREFIX (ARCPFX2 parameter)
- Bootstrap Data Sets : COPY 1 NAME
- Bootstrap Data Sets : COPY 2 NAME
- COMMAND PREFIX
Db2 VTAM LUNAME
Db2 NETWORK LUNAME- MEMBER IDENTIFIER
- MEMBER NAME
- PARAMETER MODULE
- PROC NAME
- RESYNC PORT
- SUBSYSTEM NAME
- SUBSYSTEM SEQUENCE
- SUBSYSTEM NAME (IRLM)
- WORK FILE DB
Parameter values that must be the same on every member
The list below shows the installation panel fields that must have the same values for every member of the data sharing group.
- APPL COMPAT LEVEL
- AUTH EXIT CACHE REFR
- AUTH EXIT CHECK
- CATALOG ALIAS
- DEL CF STRUCTS
- DBADM CREATE AUTH
- Db2 LOCATION NAME
- DESCRIBE FOR STATIC
- DIRECTORY AND CATALOG DATA
- DIRECTORY AND CATALOG INDEXES
- TCPIP PORT
- EVALUATE UNCOMMITTED
- EXTENDED SECURITY
- GROUP ATTACH
- GROUP NAME
- INDEX SPACE ALLOCATION
- IRLM XCF GROUP NAME
- INSTALL DD CONTROL SUPT
- LIKE_BLANK_INSIGNIFICANT in macro DSN6SPRM
- MAX UTILS PARALLELISM
- MINIMUM DIVIDE SCALE
- PAD INDEXES BY DEFAULT
- PERCENT FREE FOR UPDATE
- REAL TIME STATS
- REVOKE DEP PRIV
- SECURE PORT
- SITE TYPE
- SKIP UNCOMM INSERTS
- STATISTICS FEEDBACK
- STATISTICS HISTORY
- STATISTICS ROLLUP
- SYSTEM ADMIN 1
- SYSTEM ADMIN 2
- SYSTEM OPERATOR 1
- SYSTEM OPERATOR 2
- SECURITY ADMIN 1
- SEC ADMIN 1 TYPE
- SECURITY ADMIN 2
- SEC ADMIN 2 TYPE
- SEPARATE SECURITY
- TABLE SPACE ALLOCATION
- TEMPLATE TIME
- TCP/IP ALREADY VERIFIED
- TRACKER SITE
- UNICODE IFCIDS
- VARY DS CONTROL INTERVAL
Other recommendations
The table below shows the installation panel fields that can have the same or different values for members of a data sharing group.
| Installation panel field (parameter) name | Recommendation |
|---|---|
| DEALLOC PERIOD | Do not archive to tape. If you must, however, you should specify 0 for this parameter unless you intend to run all RECOVER jobs from the same member. Specifying a deallocation delay means that the tape is not available to any other member until the deallocation time expires. |
| For consistent results when creating objects on different members, make this default the same on all members. | |
| DEFAULT BUFFER POOL FOR USER INDEXES | For consistent results when creating objects on different members, make this default the same on all members. |
| Archive the first copy of the log to disk. | |
| DISABLE EDM RTS | For consistent results, make the value of this subsystem parameter the same on all members. |
| IMMEDIATE WRITE (IMMEDWRI parameter) | |
| READ COPY2 ARCHIVE | This option should have the same value (either YES or NO) for all members of the group. Otherwise, the parameter, as it is set on the member that owns the archive log data set, determines which copy is used. |
| READ TAPE UNITS | Do not archive to tape. If you must, however, it is vital that you have enough tape units allocated to the member doing the recovery to merge the archive logs from all members in the group that have updated the object being recovered. Thus, if there are eight members in the group, make sure you specify at least eight on this panel for each member. |
| RECORDING MAX | All members should use the maximum value of 10000, making it easier to transfer a workload from one member to another. |
| RETAINED LOCK TIMEOUT | If you have automatic restart, or some other restart automation that quickly restarts failed members, choose a non-zero value for this parameter. |
| START IRLM CTRACE | Diagnostic traces should be activated for all members of the group. The negligible performance overhead is outweighed by the benefit of easier problem resolution. Only those systems that have reached the limits of processor capacity should consider not automatically activating these traces. |