System Jobs

System jobs are created and used by the operating system to control system resources and process other system-wide requests. On the WRKACTJOB command display, system jobs are listed alphabetically after all the subsystems and user jobs. System jobs are initiated during an IPL and remain active as long as the operating system is up and running. System jobs cannot be started, ended, held, or changed by the user. There are a few system jobs which can be changed using the CHGSYSJOB command. The only attribute that can be changed by the CHGSYSJOB command is the run priority for these jobs. There are a few system jobs which will complete their work and end while the system is still active. These exceptions are QDCPOBJx, QLPSVR, and QWCBTCLNUP. Following is a list of all the systems jobs and a detailed description telling when and why they were added.

QALERT - Alert Manager

The alert manager system job performs the tasks necessary to process alerts. This includes such activities as processing alerts received from other systems, processing locally created alerts, and maintaining the sphere of control. QALERT job priority can be changed using the CHGSYSJOB command. This job was added in V2R2M0 as part of the alertable messages support.

QCMNARBxx - Communications Arbiters

The communications arbiters process work for all types of devices rather than only for communications devices. This work includes communications connect, disconnect, device locking, and error recovery processing. All device-related work is spread throughout the QCMNARBxx jobs and QSYSARB.

The QCMNARB system value determines the number of communications arbiter jobs that are started. If QCMNARB is set to *CALC, the system starts two communications arbiters per processor, with a minimum of three communications arbiters started. If QCMNARB is set to 0, the work will be run in QSYSARB. QCMNARBxx job priority can be changed using the CHGSYSJOB command. Prior to the addition of the QCMNARBxx jobs in V4R2M0, this work was done in QSYSARB

QDBFSTCCOL - Database File Statistic Collection

This job collects database file statistics. These statistics are crucial to proper database query optimization. QDBFSTCCOL was added in V5R3.

QDBSRVXR - Database Cross-Reference

QDBX###XR - Database Cross-Reference for Independent Disk Pool Group ###

This job maintains each of the file level system cross-reference files in QSYS. These files contain cross-reference information about data base files and SQL information across the system. The files all begin with the prefix of QADB in library QSYS. The primary file that must be maintained is QADBXREF, the file cross-reference file. It contains a record for each physical database, logical database, DDMF, and ALIAS file on the system. QDBSRVXR activates when a file is created, changed, deleted, restored, renamed, or it’s ownership is changed. QDBSRVXR was created in V3R1M0. QDBX###XR was created in V5R3.

QDBSRVXR2 -Database Cross-Reference 2

QDBX###XR2 - Database Cross-Reference 2 for Independent Disk Pool Group ###

This job maintains the two field-level cross-reference files. QADBIFLD in library QSYS is the field cross-reference file. QADBKFLD in library QSYS is the key field cross-reference file. QDBSRVXR2 is activated to perform its field-related work whenever a file is created, changed, or deleted. QDBSRVXR2 was added in V3R1M0 by PTF. QDBSRVXR2 job priority can be changed using the CHGSYSJOB command. QDBX###XR2 was created in V5R3.

QDBSRV01 - Database Server

QDBS###V01 - Database Server for Independent Disk Pool Group ###

This job can be viewed as the database maintenance task dispatcher. Typically, QDBSRV01 will be most active immediately following the restore of a library that contains database files. Its function includes: o Signaling to the SMAPP (System Managed Access Path Protection) Licensed Internal Code tasks that new access paths have been restored. SMAPP then determines if these access paths need to be protected.

o Preparing the list of access paths that are required to be rebuilt because the access paths were not restored. This is the list that is viewed using the EDTRBDAP command.

The number of database server jobs on the system is one plus twice the number of processors, or one plus twice the number of Auxiliary Storage Pools (ASPs), whichever is greater. The minimum started is five. QDBSRV01 is the main system job assigning work to the others. Of the remaining jobs, the first half process high priority requests, and the second half process low priority requests. For example, on a 4-way system there will be 9 QDBSRVxx system jobs. QDBSRV01 assigns work. QDBSRV02 - 05 are high priority, QDBSRV06 - 09 are low priority. These jobs were added in V2R1M0. QDBS###V01 was created in V5R3.

QDBSRVxx - Database Server (high priority)

QDBS###Vxx - Database Server (high priority) for Independent Disk Pool Group ###

These jobs perform journal and commitment control maintenance for the system and are considered quick or short running work. QDBS###Vxx was created in V5R3.

QDBSRVxx - Database Server (low priority)

QDBS###Vxx - Database Server (low priority) for Independent Disk Pool Group ###

These jobs perform access path maintenance on user database files. Typically these jobs are inactive; however, in certain cases they may activate to perform access path rebuilds. The access paths that are being maintained can be viewed using the EDTRBDAP command. Some reasons why these jobs could be active are:

o Restore of database files that were not saved with access paths

o Restore of logical files without the physical file they are based upon

o Canceling of a RGZPFM command while in process

o Invalidation of an index due to damage found upon it

o Post the operating system installation activity to complete cross-reference or other IBM® DB2® upgrade activity

o Constraint Verification. The EDTCPCST command shows constraints that are awaiting completion of such verification.

QDBS###Vxx was created in V5R3.

QDCPOBJx - Decompress System Object

These jobs decompress newly installed operating system objects as needed. There is a storage requirement for these jobs to run., If your system drops below a certain limit, these jobs terminate. The number of decompress system object jobs is the number of processors plus one. These jobs were added in V2R1M0.

QFILESYS1 - File System The file system job supports the background processing of the file system. It ensures that changes to files are written out to storage and performs general file system cleanup activities. This job was added in V3R1M0.

QJOBSCD - Job Schedule

QJOBSCD controls the job scheduling functions of the system monitoring the timers for job schedule entries and scheduled jobs. This job was added in V2R2M0 as part of the job scheduler support.

QLI###CL - Library Cleanup for Independent Disk Pool Group ###

This job cleans up libraries on independent disk pools. QLI###CL was created in V5R3.

QLI###RP - Object Cleanup for Independent Disk Pool Group ###

This job cleans up replaced objects on independent disk pool libraries. QLI###RP was created in V5R3.

QLPSVR - Software Agreements Acceptance

This job is automatically started during an IPL if online software agreements need to be accepted. The job ends when all agreements are either accepted or declined. QLPSVR was added in V5R3.

QLUR - LU 6.2 Resynchronization

QLUR handles the two-phase commit resynchronization processing. This job was added in V3R1M0 as part of the LU 6.2 communications protocol.

QLUS - Logical Unit Services

QLUS processes the event handling for logical unit devices (communications devices). It is also responsible for allocating devices to the correct communications subsystem. QLUS is one of the original system jobs on the AS/400.

QPFRADJ - Performance Adjustment

The performance adjustment system job manages changes to the storage pool sizes and activity levels. All requests to change storage pools are processed by this job. In addition, if system value QPFRADJ is set to a value of '2' or '3,' this job dynamically changes the sizes and activity levels of storage pools to improve the performance of the system. As of V4R3M0, the IPL performance tuning (system value QPFRADJ is set to '1' or '2,') is also run in QPFRADJ. Prior to V4R3M0, IPL tuning ran in the SCPF process. QPFRADJ was added in V2R1M0.

QQQTEMP1 and QQQTEMP2 - Database Parallelism

The database parallelism system jobs perform asynchronous database processing for the DB2 Multisystem. If users query distributed files, the jobs are used to speed up the queries by doing certain tasks in parallel. These jobs were added in V3R7M0 as part of DB2 Multisystem support.

QSPLMAINT - System Spool Maintenance

QSPMN##### - System Spool Maintenance for Independent Disk Pool Group ###

QSPLMAINT performs system spool maintenance functions. For example: o When the job status is DLTSPLF, the job is clearing data from a spool database member after the user has specified to delete a spooled file.

o When the job status is RCLSPLSTG, the job is deleting unused and empty spool database members in the QSPL library. System value QRCLSPLSTG tells the system how long to retain these empty spool database files.

o When the job status is SPLCLNUP, the job is performing spool cleanup operation. After an abnormal IPL:

-- Jobs are moved from destroyed job queues to QSPRCLJOBQ in QRCL.

-- Spooled files are moved from destroyed output queues to QSPRCLOUTQ in library QRCL.

-- Spooled files on destroyed device output queues are moved to the re-created device output queues

o When a damaged spooled database file is encountered, spooled files with data are deleted.

QSPLMAINT job priority can be changed using the CHGSYSJOB command. QSPLMAINT was added in V2R1M1. QSPMN##### was created in V5R3.

QSPPF##### - System Spool PRTQ Updater for Independent Disk Pool Group ###

This job performs spooled file operations for the specific independent disk pool group. QSPPF##### was created in V5R3.

QSYSARB - System Arbiter

The system arbiter provides the environment for the running of high-priority functions. It handles system resources and keeps track of the state of the system. QSYSARB is the central and highest priority job within the operating system. The system arbiter responds to system-wide events that must be handled immediately and those that can be handled more efficiently by a single job than multiple jobs. QSYSARB is responsible for processing communications requests, device locking, line, controller, and device configuration, and handling of other system-wide resources. The system arbiter is one of the original system jobs on the operating system. Much of the work done in other system jobs -- the other system arbiters, the communications arbiters, the database cross-reference jobs, and the system communications jobs -- were all once handled by a single system arbiter.

QSYSARB2 - System Arbiter

System Arbiter2 is responsible for managing tape resources, handling Command Analyzer spaces for command processing, and other system-wide processing for the operating system. QSYSARB2 was created in V3R6M0 when QSYSARB was divided into multiple arbiters.

QSYSARB3 - System Arbiter

System Arbiter3 is responsible for creating and maintaining the job structures on the system. Whenever temporary or permanent job structures are required for job initiation, the request is processed by QSYSARB3. QSYSARB3 was created in V3R6M0 when QSYSARB was divided into multiple arbiters.

QSYSARB4 - System Arbiter

System Arbiter4 is responsible for starting and ending subsystems. This includes the initial processing for PWRDWNSYS. QSYSARB4 was created in V3R6M0 when QSYSARB was divided into multiple arbiters.

QSYSARB5 - System Arbiter

System Arbiter5 is responsible for processing machine events. This includes handling events to support Auxiliary power, Continuous Powered Mainstore, System ASP and storage threshold, and Lock table limits. Usually, the machine events are handled and a corresponding CPF message is sent to QSYSOPR and QHST. QSYSARB5 was created in V3R6M0 when QSYSARB was divided into multiple arbiters.

QSYSCOMM1 - System Communications

The system communications job handles some communications and I/O system activity. QSYSCOMM1 job priority can be changed using the CHGSYSJOB command. This job was added in V3R2M0.

QTAPARB - Tape Devices

This job processes work related to tape devices including device locking and error recovery processing. QTAPARB was created in V5R3.

QWCBTCLNUP - Job Table Cleanup

QWCBTCLNUP is used during the IPL to ensure that the job structures are available for use. It usually completes processing before the end of the IPL; however, it can continue running after the IPL if there are a lot of job structures to clean up. This system job ends when it completes processing. This job was added in V2R1M0 when the job table cleanup was moved out of the SCPF process.

Q400FILSVR - Remote File System Communications

The remote file system communication system job performs the Common Programming Interface Communications (APPN or APPC) for the Remote File System. This job was added in V3R6M0 as part of the remote file support.

SCPF - Start Control Program Function

The SCPF system job is the central job during the operating system IPL, providing the environment and directing the functions necessary to start the operating system. SCPF starts all the other system jobs, (except QLUS, which is started by QSYSARB) and brings the system up to a usable state. SCPF remains active after the IPL providing an environment for the running of low-priority and possibly long-running system functions. SCPF also runs during the PWRDWNSYS processing and is the job that terminates the machine processing. SCPF is one of the original system jobs on the operating system.