An unlimited number of Adabas Parallel Services nucleus clusters, each with up to 31 members sharing a common database, can be defined for an operating system image.
The ADACOM initialization task (
must be run in order to set up the environment, and it must be maintained in
order to monitor and control the nuclei of one or more Adabas Parallel Services clusters.
ADACOM initialization parameters specify the Router ID / DBID combinations (sets) that the ADACOM is to manage.
The Router ID identifies the SVC number on z/OS or z/VSE. The Router ID value must be the same within a cluster; for different clusters, the same or different Router IDs may be used.
The DBID identifies the external physical database shared by a particular cluster of nuclei and known to the application.
Other ADACOM parameters are discussed in the following sections.
Although a single ADACOM job can run all Router ID / DBID sets in an Adabas Parallel Services environment, it is possible to run multiple ADACOM tasks simultaneously with the same, mixed, or completely different Router ID / DBID sets. An ADACOM subtask is attached to each Router ID / DBID set for each ADACOM task in which it occurs.
ADACOM prints global messages that apply to all Router ID / DBID sets to two output data sets or files. One is identified by the DD or link name Pssddddd, where ss is the last two digits of the SVC number and ddddd is the DBID. The Pssddddd data set or file is also used by Adabas Cluster Services. The second output data set or file is identified by the DD or link name Dssddddd and is used only by Adabas Parallel Services. ADACOM uses the Dssddddd data set or file to record which cache and lock spaces it allocates and releases for the associated cluster database, as the Adabas Parallel Services nuclei start and end.
On z/OS systems, ADACOM automatically allocates these data sets in the spool with SYSOUT=*, if they are not explicitly specified.
For a sample job to run ADACOM, read the z/OS section Create a Startup Procedure for ADACOM.
|DBID||the database to be used.||1||65000||none|
The DBID parameter designates the ID of an Adabas Parallel Services cluster's external physical database; that is, the database number that the user programs address to send commands to the single physical database of an Adabas Parallel Services nucleus cluster.
This number must be unique among all Adabas database IDs, NUCIDs, Natural buffer pool IDs, etc.
|FORCE||whether ADACOM forces a restart after an abnormal termination.||YES | NO||NO|
If Adabas Parallel Services believes there are still active nuclei, ADACOMs, or users on an image after a termination, a NU parameter value that is different from the NU value already in effect will not be recognized on restart. If you are certain that Adabas Parallel Services is wrong in its belief, you can use FORCE=YES to force a clean restart.
Note, however, that if a cluster nucleus or an ADACOM with the same SVC number or IDTNAME is active on the image where FORCE=YES is used, it will crash.
|LOC||where to place the PLXCB structures that maintain information about nuclei and users.||CSA | DSP||CSA|
To provide relief from 31-bit ECSA storage constraints you may direct the PLXCB be placed in a dataspace. This is available only under z/OS.
|NU||the number of users that can be active in parallel on cluster nuclei in the image.||20||16 777 215||200|
In the extended CSA (ECSA), the SVCCLU maintains a user table with entries (UTEs) containing information about every active user in the cluster nuclei on the operating system image. A UTE is assigned when a user issues an OP command or (if the user did not issue an OP command) at the first Adabas command. The UTE is released when the user issues a CL command or when a timeout occurs.
The ADACOM NU parameter specifies the number of concurrent users (UTEs) allowed for all the nuclei of a cluster. The first ADACOM started governs the value for NU: different values set for subsequent nuclei or ADACOMs are ignored.
To manually change the NU value, you must stop all cluster nuclei and ADACOM tasks in the image, modify the NU value for all the nucleus and ADACOM jobs, and then restart.
When the NU parameter is set to zero, any space allocated for the user table is freed, the Adabas Parallel Services control block is freed, and the ADACOM task terminates. However, if ADACOM believes that there are active nuclei, ADACOMs, or users, and FORCE=YES is not used, no action is taken.
For example, the following parameter would run the Adabas Parallel Services cluster nuclei with 500 elements in the user table:
|SVC||the supervisor call number to be used for the Adabas Parallel Services nucleus cluster session.||
z/VSE: see text
The SVC is used to perform various Adabas internal functions; the number is used to communicate between the users and the database.
The SVC number is specified as an integer and must correspond to the number used for the Adabas SVC (ADASVC).
For z/OS, valid SVC values are 200-255.
For z/VSE, 45 is the recommended value but any free SVC value can be used. Read the Adabas installation documentation for information about finding free z/VSE Adabas SVC values.
For example, the following parameter will execute an Adabas Parallel Services nucleus cluster session on a z/OS image using ADASVC 202.