HP OpenVMS Systems Documentation
Content starts here

OpenVMS System Management Utilities Reference Manual
Previous Contents Index

LOAD_SYS_IMAGES controls the loading of system images described in the system image data file, VMS$SYSTEM_IMAGES. This parameter is a bit mask.

On VAX systems, the following bit is defined:

Bit Description
0 (SGN$V_LOAD_SYS_IMAGES) Enables loading alternate execlets specified in VMS$SYSTEM_IMAGES.DATA.

On Alpha systems, the following bits are defined:

Bit Description
0 (SGN$V_LOAD_SYS_IMAGES) Enables loading alternate execlets specified in VMS$SYSTEM_IMAGES.DATA.
1 (SGN$V_EXEC_SLICING) Enables executive slicing.
2 (SGN$V_RELEASE_PFNS) Enables releasing unused portions of the Alpha huge pages.

These bits are on by default. Using conversational bootstrap exec slicing can be disabled.

LOCKDIRWT (A)

LOCKDIRWT determines the portion of lock manager directory that this system handles. The default value is usually adequate.

LOCKIDTBL (A,F,M)

LOCKIDTBL sets the initial number of entries in the system Lock ID table and defines the amount by which the Lock ID table is extended whenever the system runs out of locks. One entry must exist for each lock in the system; each entry requires 4 bytes.

For simple timesharing systems, the default value is adequate. If your application uses many locks, as in the case of heavy RMS file sharing or a database management application, you should increase this parameter. When you change the value of LOCKIDTBL, examine the value of RESHASHTBL and change it if necessary.

The OpenVMS Lock Management facility is described in the OpenVMS Programming Concepts Manual. You can monitor locks with the MONITOR LOCK command of the Monitor utility.

LOCKIDTBL_MAX

LOCKIDTBL_MAX is obsolete beginning with OpenVMS Version 7.1.

LOCKRETRY

LOCKRETRY establishes the number of attempts made to lock a multiprocessor data structure.

This special parameter is used by Compaq and is subject to change. Do not change this parameter unless Compaq recommends that you do so.

LONGWAIT (A on Alpha,D,G,M)

LONGWAIT defines how much real time (in seconds) must elapse before the swapper considers a process to be temporarily idle. This parameter is applied to local event flag (LEF) and hibernate (HIB) waits to detect such conditions as an inactive terminal or ACP.

LRPCOUNT

This parameter has been obsolete since OpenVMS Version 6.0.

LRPSIZE (G,M)

This parameter has been obsolete since OpenVMS Version 6.0.

MAXBOBMEM (D)

(Alpha only) MAXBOBMEM defines the maximum amount of physical memory, measured in pagelets, that can be associated with a single buffer object created by a process in user mode. The default value of 0 means there is no system-imposed limit on the size of a buffer object.

Other MAXBOB* parameters are obsolete in OpenVMS Version 7.3.

MAXBUF (D)

MAXBUF sets the maximum allowable size for any single buffered I/O packet. Buffered I/O packets are allocated from the permanently resident nonpaged dynamic pool. The terminal, mailbox, and printer device drivers are examples of device drivers that perform buffered I/O.

The number of bytes specified in the I/O request plus the size of a driver-dependent and function-dependent header area determine the required buffered I/O packet size. The size of the header area is a minimum of 16 bytes; there is no absolute upper limit. However, this header area is usually a few hundred bytes in size.

On OpenVMS VAX systems beginning with Version 7.1, the default value is 4112. The default value on OpenVMS Alpha systems continues to be 8192.

The maximum value of MAXBUF is 64000 bytes.

MAXCLASSPRI (D)

If class scheduling is enabled, MAXCLASSPRI sets the maximum range in the priority range of class-scheduled processes.

This special parameter is used by Compaq and is subject to change. Do not change this parameter unless Compaq recommends that you do so.

MAXPROCESSCNT (A,F,G,M)

MAXPROCESSCNT sets the number of process entry slots allocated at bootstrap time. One slot is required for each concurrent process on the system. Each slot requires 6 bytes of permanently resident memory.

The default value is normally configured to allow you to create the desired number of processes. If the following message appears, you need to increase the value of MAXPROCESSCNT: 


%SYSTEM-F-NOSLOT,  No PCB to create process

MAXQUEPRI (D)

MAXQUEPRI determines the highest scheduling priority that can be assigned to jobs entered in batch and output (printer, server, and terminal) queues without the submitter process having OPER or ALTPRI privilege. The value of this parameter can range from 0 to 255; the default is 100. The value of MAXQUEPRI should be greater than or equal to DEFQUEPRI.

Note
MAXQUEPRI refers to relative queue scheduling priority, not to the execution priority of the job.

MAXSYSGROUP (D)

MAXSYSGROUP sets the highest value that a group number can have and still be classified as a system UIC group number. Note that the specification is not in octal unless preceded by the %O radix indicator. This parameter is normally left at 8 (10 octal).

MC_SERVICES_P0 (D)

(Alpha only) MC_SERVICES_P0 controls whether other MEMORY CHANNEL nodes in the cluster continue to run if this node bugchecks or shuts down.

A value of 1 causes other nodes in the MEMORY CHANNEL cluster to crash with bugcheck code MC_FORCED_CRASH if this node bugchecks or shuts down.

The default value is 0. A setting of 1 is intended only for debugging purposes; the parameter should otherwise be left at its default value.

MC_SERVICES_P1 (D)

(Alpha only) This special parameter is reserved for Compaq use. Its value must be the same on all nodes connected by MEMORY CHANNEL.

MC_SERVICES_P2

(Alpha only) MC_SERVICES_P2 specifies whether to load the PMDRIVER (PMA0) MEMORY CHANNEL cluster port driver.

PMDRIVER is a new driver that serves as the MEMORY CHANNEL cluster port driver. It works together with MCDRIVER (the MEMORY CHANNEL device driver and driver interface) to provide MEMORY CHANNEL clustering. If PMDRIVER is not loaded, cluster connections are not made over the MEMORY CHANNEL interconnect.

The default value is 1, which causes PMDRIVER to be loaded when you boot the system. When you run CLUSTER_CONFIG.COM and select the MEMORY CHANNEL option, PMDRIVER is loaded automatically when you reboot the system.

Compaq recommends that this value not be changed. This parameter value must be the same on all nodes connected by MEMORY CHANNEL.

MC_SERVICES_P3 (D)

(Alpha only) MC_SERVICES_P3 specifies the maximum number of tags supported. The maximum value is 2048, and the minimum value is 100.

The default value is 800. Compaq recommends that this value not be changed. This parameter value must be the same on all nodes connected by MEMORY CHANNEL.

MC_SERVICES_P4

(Alpha only) MC_SERVICES_P4 specifies the maximum number of regions supported. The maximum value is 4096, and the minimum value is 100.

The default value is 200. Compaq recommends that this value not be changed. This parameter value must be the same on all nodes connected by MEMORY CHANNEL.

MC_SERVICES_P5 (D)

(Alpha only) MC_SERVICES_P5 is reserved for Compaq use only and must remain at the default value of 8000000. This value must be the same on all nodes connected by MEMORY CHANNEL.

MC_SERVICES_P6

(Alpha only) MC_SERVICES_P6 specifies MEMORY CHANNEL message size, the body of an entry in a free queue, or a work queue. The maximum value is 65536, and the minimum value is 544.

The default value is 992. This value is suitable in all cases except for systems with highly constrained memory. For such systems, you can reduce the memory consumptions of MEMORY CHANNEL by slightly reducing the default value of 992. The value of MC_SERVICES_P6 must always be equal to or greater than the result of the following calculations:

  1. Select the larger of SCS_MAXMSG and SCS_MAXDG.
  2. Round that value up to the next quadword.

The value of MC_SERVICES_P6 must be the same on all nodes connected by MEMORY CHANNEL.

MC_SERVICES_P7 (D)

(Alpha only) MC_SERVICES_P7 specifies whether to suppress or display messages about MEMORY CHANNEL activities on this node. This parameter can be set to a value of 0, 1, or 2:
  • A value of 0 indicates nonverbose mode: no informational messages appear on the console or in the error log.
  • A value of 1 indicates verbose mode: informational messages from both MCDRIVER and PMDRIVER appear on the console and in the error log.
  • A value of 2 provides the same output as a value of 1, with the addition of PMDRIVER stalling and recovery messages.

The default value is 0. Compaq recommends that this value not be changed except while debugging MEMORY CHANNEL problems or adjusting the MC_SERVICES_P9 parameter.

MC_SERVICES_P8

(Alpha only) MC_SERVICES_P8 is reserved for Compaq use only and must remain at the default value of 0. The value must be the same on all nodes connected by MEMORY CHANNEL.

MC_SERVICES_P9

(Alpha only) MC_SERVICES_P9 specifies the number of initial entries in a single channel's free queue. The maximum value is 2048, and the minimum value is 10.

Note that MC_SERVICES_P9 is not a dynamic parameter; you must reboot the system after each change for that change to take effect.

The default value is 150. Compaq recommends that this value not be changed.

The value of MC_SERVICES_P9 must be the same on all nodes connected by MEMORY CHANNEL.

MINCLASSPRI (D)

If class scheduling is enabled, MINCLASSPRI sets the minimum range in the priority range of class-scheduled processes.

This special parameter is used by Compaq and is subject to change. Do not change this parameter unless Compaq recommends that you do so.

MINPRPRI

This parameter is not used on OpenVMS VAX or Alpha systems.

MINWSCNT (A)

The value specified by MINWSCNT is added to the size of the process header to establish the minimum working set size.

On VAX systems, MINWSCNT sets the minimum number of fluid pages (pages not locked in the working set) required for the execution of a process. The value of MINWSCNT must provide sufficient space to execute any VAX instruction. Theoretically, the longest instruction requires 52 pages; however, all code can run with 20 fluid pages. An insufficient value may inhibit system performance or even put a process into an infinite loop on some instructions.

On Alpha systems, MINWSCNT sets the minimum number of pages required for the execution of a process. The default value is 20; the minimum value is 10.

MMG_CTLFLAGS (A,D)

MMG_CTLFLAGS is a bit mask used to enable and disable proactive memory reclamation mechanisms. Beginning with OpenVMS Version 7.2, you can control when memory is tested. This helps reduce the time between when you turn on the system and when you log in to an AlphaServer 4100 computer. Bit 2 in the parameter controls deferred memory testing.

The following bit mask values are defined:

Bit Description
0 Reclamation enabled by trimming from periodically executing, but otherwise idle processes. This occurs when the size of the free list drops below two times FREEGOAL.
1 Reclamation enabled by outswapping processes that have been idle for longer than LONGWAIT seconds. This occurs when the size of the free list drops below FREELIM.
2 Controls deferred memory testing:
  • If the bit is clear (the default), OpenVMS tests memory in the background and not necessarily before the bootstrap process has completed.
  • If the bit is set, all memory is tested by the end of EXEC_INIT in the system bootstrap process (that is, before IPL is lowered from 31).
3-7 Reserved for future use.

MPDEV_D1

(Alpha only) MPDEV_D1 is reserved for use by the operating system.

MPDEV_ENABLE

(Alpha only) MPDEV_ENABLE enables the formation of multipath sets when set to ON (1). If set to OFF (0), the formation of additional multipath sets is disabled. However, existing multipath sets remain in effect. The default is ON.

MPDEV_LCRETRIES

(Alpha only) MPDEV_LCRETRIES controls the number of times the system retries locally connected paths before moving on to local unconnected paths or to an MSCP served path to the device. The valid range for retries is 1 through 256. The default is 1.

MPDEV_POLLER

(Alpha only) MPDEV_POLLER enables polling of the paths to multipath set members when set to ON (1). Polling allows early detection of errors on inactive paths. If a path becomes unavailable or returns to service, the system manager is notified with an OPCOM message. If set to OFF (0), multipath polling is disabled. The default is ON.

MPDEV_REMOTE

(Alpha only) MPDEV_REMOTE enables MSCP served disks to become members of a multipath set when set to ON (1). If set to OFF (0), only local paths to a SCSI or Fibre Channel device will be used in the formation of additional multipath sets.

However, setting this parameter to OFF will not have any effect on existing multipath sets that have remote paths. The default is OFF.

For OpenVMS Alpha Version 7.3, this parameter must remain set to the default value of OFF (0). This restriction will be removed in a future release of OpenVMS.

MPW_HILIMIT (A,G)

MPW_HILIMIT sets an upper limit for the modified-page list. When the list accumulates the number of pages specified by this limit, writing of the list begins. The pages that are written are then transferred to the free-page list.

If MPW_HILIMIT is too low, excessive page faulting can occur from the page file. If it is too high, too many physical pages can be consumed by the modified-page list.

If you increase MPW_HILIMIT, you might also need to increase MPW_WAITLIMIT. Note that if MPW_WAITLIMIT is less than MPW_HILIMIT, a system deadlock occurs. The values for the two parameters are usually equal.

MPW_IOLIMIT (A on Alpha)

MPW_IOLIMIT specifies the number of outstanding I/Os to the modified-page writer.

MPW_LOLIMIT (A,G)

MPW_LOLIMIT sets a lower limit for the modified-page list. When writing of the list causes the number of pages on the list to drop to or below this limit, writing stops.

MPW_LOLIMIT ensures that a certain number of pages are available on the modified-page list for page faults. If the number is too small, the caching effectiveness of the modified-page list is reduced. If it is too high, less memory is available for processes, so that swap (and page) may increase.

MPW_LOWAITLIMIT (A,D)

MPW_LOWAITLIMIT specifies the threshold at which processes in the miscellaneous wait state MPWBUSY are allowed to resume. MPW_LOWAITLIMIT increases system performance for fast processors with large memories by reducing the amount of time processes spend in the MPWBUSY wait state.

MPW_PRIO

MPW_PRIO sets the priority of I/O transfers initiated by the modified page writer. The maximum value is 31, the minimum is 0, and the default is 4.

This special parameter is used by Compaq and is subject to change. Do not change this parameter unless Compaq recommends that you do so.

MPW_THRESH (A on Alpha,D)

MPW_THRESH sets a lower bound of pages that must exist on the modified-page list before the swapper writes this list to acquire free pages. If this requirement is met, the swapper tries to write the modified-page list rather than taking pages away from or swapping out a process.

MPW_WAITLIMIT (A,D)

MPW_WAITLIMIT sets the number of pages on the modified-page list that causes a process to wait until the next time the modified-page writer writes the modified list. This parameter limits the rate at which any single process can produce modified pages. If this value is less than MPW_HILIMIT, a system deadlock occurs. The value for this parameter is normally equal to MPW_HILIMIT.

MPW_WRTCLUSTER (A,G)

MPW_WRTCLUSTER sets the number of pages to be written during one I/O operation from the modified-page list to the page file or a section file. The actual size of the cluster may be limited by the number of pages available for the I/O operation. This parameter can range in value from 16 to 120, in multiples of 8. Each page in the cluster requires 6 bytes of permanently resident memory.

If MPW_WRTCLUSTER is too small, it takes many I/O operations to empty the modified-page list. If MPW_WRTCLUSTER is too large for the speed of the disk that holds the page file, other I/O operations are held up for the modified-page list write.

On VAX systems, the MPW_WRTCLUSTER default value and maximum value is 120 512-byte pages; its minimum value is 16 512-byte pages.

On Alpha systems, the MPW_WRTCLUSTER default value is 64 8192-byte pages; its maximum value is 512 8192-byte pages; and its minimum value is 16 8192-byte pages.

MSCP_BUFFER (A,F)

This buffer area is the space used by the server to transfer data between client systems and local disks.

On VAX systems, MSCP_BUFFER specifies the number of pages to be allocated to the MSCP server's local buffer area.

On Alpha systems, MSCP_BUFFER specifies the number of pagelets to be allocated to the MSCP server's local buffer area.

MSCP_CMD_TMO (D)

MSCP_CMD_TMO is the time in seconds that the OpenVMS MSCP server uses to detect MSCP command timeouts. The MSCP Server must complete the command within a built-in time of approximately 40 seconds plus the value of the MSCP_CMD_TMO parameter.

The MSCP_CMD_TMO default value of 0 is normally adequate. A value of 0 provides the same behavior as in previous releases of OpenVMS (which did not have an MSCP_CMD_TMO system parameter). A nonzero setting increases the amount of time before an MSCP command times out.

If command timeout errors are being logged on client nodes, setting the parameter to a nonzero value on OpenVMS servers reduces the number of errors logged. Increasing the value of this parameter reduces the numb client MSCP command timeouts and increases the time it takes to detect faulty devices.

If you need to decrease the number of command timeout errors, Compaq recommends that you set an initial value of 60. If timeout errors continue to be logged, you can increase this value in increments of 20 seconds.

MSCP_CREDITS

MSCP_CREDITS specifies the number of outstanding I/O requests that can be active from one client system.

MSCP_LOAD (A)

MSCP_LOAD controls the loading of the MSCP server during a system boot. Specify one of the following values:
Value Description
0 Do not load the MSCP server. This is the default value.
1 Load the MSCP server and serve disks as specified by the MSCP_SERVE_ALL parameter.

MSCP_SERVE_ALL

MSCP_SERVE_ALL is a bit mask that controls disk serving in an OpenVMS Cluster. A disk is served regardless of its allocation class unless bit 3 has a value of 1.

Starting with OpenVMS Version 7.2, the serving types are implemented as a bit mask. To specify the type of serving your system will perform, locate the type you want in the following table and specify its value. For some systems, you may want to specify two serving types, such as serving the system disk and serving locally attached disks. To specify such a combination, add the values of each type, and specify the sum.

In a mixed-version cluster that includes any systems running OpenVMS Version 7.1-x or earlier, serving all available disks is restricted to serving all disks except those whose allocation class does not match the system's node allocation class (pre-Version 7.2). To specify this type of serving, use the value 9 (which sets bit 0 and bit 3).

The following table describes the serving type controlled by each bit and its decimal value.

Bit and Value When Set Description
Bit 0 (1) Serve all available disks (locally attached and those connected to HS x and DSSI controllers). Disks with allocation classes that differ from the system's allocation class (set by the ALLOCLASS parameter) are also served if bit 3 is not set.
Bit 1 (2) Serve locally attached (non-HS x and DSSI) disks.
Bit 2 (4) Serve the system disk. This is the default setting. This setting is important when other nodes in the cluster rely on this system being able to serve its system disk. This setting prevents obscure contention problems that can occur when a system attempts to complete I/O to a remote system disk whose system has failed.
Bit 3 (8) Restrict the serving specified by bit 0. All disks except those with allocation classes that differ from the system's allocation class (set by the ALLOCLASS parameter) are served.

This is pre-Version 7.2 behavior. If your cluster includes systems running OpenVMS 7.1- x or earlier, and you want to serve all available disks, you must specify 9, the result of setting this bit and bit 0.

Although the serving types are now implemented as a bit mask, the values of 0, 1, and 2, specified by bit 0 and bit 1, retain their original meanings:

  • 0 --- Do not serve any disks (the default for earlier versions of OpenVMS).
  • 1 --- Serve all available disks.
  • 2 --- Serve only locally attached (non-HSx and non-DSSI) disks.

If the MSCP_LOAD system parameter is 0, MSCP_SERVE_ALL is ignored.

MULTIPROCESSING

MULTIPROCESSING controls the loading of the system synchronization image.

Specify one of the following values:

Value Description
0 Load the uniprocessing synchronization image SYSTEM_SYNCHRONIZATION_UNI.EXE.
1 If the CPU type is capable of SMP and two or more CPUs are present on the system, load the full-checking multiprocessing synchronization image SYSTEM_SYNCHRONIZATION.EXE. Otherwise, load the uniprocessing synchronization image SYSTEM_SYNCHRONIZATION_UNI.EXE.
2 Always load the full-checking version SYSTEM_SYNCHRONIZATION.EXE, regardless of system configuration or CPU availability.
3 If the CPU type is capable of SMP and two or more CPUs are present on the system, load the optimized streamlined multiprocessing image:
  • On VAX systems, this image is SYSTEM_SYNCHRONIZATION_SPC.EXE.
  • On Alpha systems, this image is SYSTEM_SYNCHRONIZATION_MIN.EXE.

Otherwise, load the uniprocessing synchronization image SYSTEM_SYNCHRONIZATION_UNI.EXE. The default value is 3.

4 Always load the streamlined multiprocessing image SYSTEM_SYNCHRONIZATION_MIN.EXE, regardless of system configuration or CPU availability.

Setting the SYSTEM_CHECK parameter to 1 has the effect of setting MULTIPROCESSING to 2.

MULTITHREAD (A)

MULTITHREAD controls the availability of kernel threads functions. Specify one of the following values:
Value Description
0 Both Thread Manager upcalls and the creation of multiple kernel threads are disabled.
1 Thread Manager upcalls are enabled; the creation of multiple kernel threads is disabled.
2-256 (Alpha only) Both Thread Manager upcalls and the creation of multiple kernel threads are enabled. The number specified represents the maximum number of kernel threads that can be created for a single process.

The maximum value for MULTITHREAD is 256.

MVTIMEOUT (A on Alpha,D)

MVTIMEOUT is the time in seconds that a mount verification attempt continues on a given disk volume. If the mount verification does not recover the volume within that time, the I/O operations outstanding to the volume terminate abnormally.

NET_CALLOUTS (D)

NET_CALLOUTS is normally set to 0. A value of 255 indicates that no attempt is to be made to assign a new proxy connection to an active server, but that a new process must be started to invoke the installation security policy callout modules in LOGINOUT.EXE. Values 1 through 254 are reserved for future use.

NISCS_CONV_BOOT

NISCS_CONV_BOOT controls whether a conversational boot is permitted during a remote system boot. The default value of 0 specifies that conversational boots are not permitted.

NISCS_LAN_OVRHD

Beginning in OpenVMS Version 7.3, this parameter is obsolete.

NISCS_LOAD_PEA0

NISCS_LOAD_PEA0 controls whether the NI-SCS port driver PEDRIVER is loaded during system boot. The default of 0 specifies that the PEDRIVER is not loaded.

NISCS_MAX_PKTSZ (A on Alpha)

This parameter specifies an upper limit on the size, in bytes, of the user data area in the largest packet sent by NISCA on any local area network (LAN).

NISCS_MAX_PKTSZ allows the system manager to change the packet size used for cluster communications on network communication paths. PEDRIVER automatically allocates memory to support the largest packet size that is usable by any virtual circuit connected to the system up to the limit set by this parameter. Its default values are different for OpenVMS Alpha and OpenVMS VAX:

  • On Alpha, to optimize performance, the default value is the largest packet size currently supported by OpenVMS.
  • On VAX, to conserve memory, the default value is the Ethernet packet size.

PEDRIVER uses NISCS_MAX_PKTSZ to compute the maximum amount of data to transmit in any LAN packet:

Previous Next Contents Index