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HP OpenVMS Systems Documentation
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HP OpenVMS System Management Utilities Reference Manual

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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. HP 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 HP 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. HP 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 HP and is subject to change. Do not change this parameter unless HP recommends that you do so.

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 and I64 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 or disable memory management-related activities.

The first two bits, 0 and 1, control the proactive memory reclamation mechanisms. Bit 2 controls deferred memory testing.

The following bit mask values are defined:

Bit Description
0 If this bit is set, reclamation is enabled by trimming from periodically executing, but otherwise idle, processes. This occurs when the size of the free list drops below two times FREEGOAL. This function is disabled if the bit is clear.
1 If this bit is set, reclamation is enabled by outswapping processes that have been idle for longer than LONGWAIT seconds. This occurs when the size of the free list drops below FREEGOAL. This function is disabled if the bit is clear.
2 Controls deferred memory testing (only on AlphaServer 4100 systems). You can use this bit to speed up elapsed bootstrap time by controlling when memory is tested:
  • If the bit is clear (the default), OpenVMS tests memory as a background activity, which might or might not complete before the end of the bootstrap process.
  • If the bit is set, all memory is tested in the bootstrap process by the end of the EXEC_INIT phase (that is, before IPL is lowered from 31).
3-7 Reserved for future use.

MPDEV_AFB_INTVL

(Alpha and I64) MPDEV_AFB_INTVL specifies the automatic failback interval in seconds. The automatic failback interval is the minimum number of seconds that must elapse before the system attempts another failback from an MSCP path to a direct path on the same device.

MPDEV_POLLER must be set to ON to enable automatic failback. You can disable automatic failback without disabling the poller by setting MPDEV_AFB_INTVL to 0. The default is 300 seconds.

MPDEV_D*

(Alpha and I64) MPDEV_D1 through MPDEV_D4 are reserved for use by the operating system.

MPDEV_ENABLE

(Alpha and I64) MPDEV_ENABLE enables the formation of multipath sets when set to ON (1). If MPDEV_ENABLE is set to OFF (0), the formation of additional multipath sets and the addition of new paths to existing multipath sets are disabled. However, existing multipath sets remain in effect. The default is ON.

MPDEV_REMOTE and MPDEV_AFB_INTVL have no effect when MPDEV_ENABLE is set to OFF.

MPDEV_LCRETRIES

(Alpha and I64) MPDEV_LCRETRIES controls the number of times the system retries the direct paths to the controller that the logical unit is online to, before moving on to direct paths to the other controller, 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 and I64) 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. When set to OFF (0), multipath polling is disabled. The default is ON. Note that this parameter must be set to ON to use the automatic failback feature.

MPDEV_REMOTE

(Alpha and I64) MPDEV_REMOTE enables MSCP served paths to become members of a multipath set when set to ON (1). When set to OFF (0), only local paths to a SCSI or Fibre Channel device is used in the formation of additional multipath sets. However, setting this parameter to OFF does not have any effect on existing multipath sets that have remote paths.

To use multipath failover to a served path, MPDEV_REMOTE must be enabled on all systems that have direct access to shared SCSI/Fibre Channel devices. The first release to provide this feature is OpenVMS Alpha Version 7.3--1. Therefore, all nodes on which MPDEV_REMOTE is enabled must be running OpenVMS Alpha Version 7.3--1 (or later).

If MPDEV_ENABLE is set to OFF (0), the setting of MPDEV_REMOTE has no effect because the addition of all new paths to multipath sets is disabled. The default is ON.

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 and I64)

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 HP and is subject to change. Do not change this parameter unless HP recommends that you do so.

MPW_THRESH (A on Alpha and I64,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 and I64 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 and I64 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, HP 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.

The default value is currently 32. Unless a system has very constrained memory available, HP recommends that these values not be increased.

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 (prior to 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 and I64 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 (D,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.

MVSUPMSG_INTVL (D)

(Alpha and I64) The system suppresses mount verification start and end messages for fibre channel disk devices if mount verification completes on the first attempt and if mount verification does not occur too often. MVSUPMSG_NUM and this parameter establish this limit.

The system issues a mount verification message after a sequence of MVSUPMSG_NUM mount verifications have gone unannounced on a specific fibre channel disk device within a span of MVSUPMSG_INTVL seconds.

If this parameter is zero, all mount verification messages are announced.

MVSUPMSG_NUM (D)

(Alpha and I64) The system suppresses mount verification start and end messages for fibre channel disk devices if mount verification completes on the first attempt and if mount verification does not occur too often. MVSUPMSG_INTVL and this parameter establish this limit.

The system issues a mount verification message after a sequence of MVSUPMSG_NUM mount verifications have gone unannounced on a specific fibre channel disk device within a span of MVSUPMSG_INTVL seconds.

If this parameter is zero, all mount verification messages are announced.

MVTIMEOUT (A on Alpha and I64,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_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 and I64)

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/I64 and OpenVMS VAX:

  • On Alpha and I64, 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: 


LAN packet size <= LAN header (padded Ethernet format)
                   + NISCS_MAX_PKTSZ
                   + NISCS checksum (only if data checking
                                     is enabled)
                   + LAN CRC or FCS

The actual packet size automatically used by PEDRIVER might be smaller than the NISCS_MAX_PKTSZ limit for any of the following reasons:

  • On a per-LAN path basis, if PEdriver determines that the LAN path between two nodes, including the local and remote LAN adapters and intervening LAN equipment, can only convey a lesser size.
    In other words, only nodes with large-packet LAN adapters connected end-to-end by large-packet LAN equipment can use large packets. Nodes connected to large-packet LANs but having an end-to-end path that involves an Ethernet segment restrict packet size to that of an Ethernet packet (1498 bytes).
  • For performance reasons, PEDRIVER might further limit the upper bound on packet size so that the packets can be allocated from a lookaside list in the nonpaged pool.

The actual memory allocation includes the required data structure overhead used by PEDRIVER and the LAN drivers, in addition to the actual LAN packet size.

The following table shows the minimum NISCS_MAX_PKTSZ value required to use the maximum packet size supported by specified LAN types:

Type of LAN Minimum Value for NISCS_MAX_PKTSZ
Ethernet 1498
FDDI 4468
Gigabit Ethernet 8192
ATM 7606

Note that the maximum packet size for some Gigabit Ethernet adapters is larger than the maximum value of NISCS_MAX_PKTSZ (8192 bytes). See the LAN_FLAGS parameter for a description of how to enable jumbo frames on Gigabit Ethernet---that is, packet sizes larger than those noted for Ethernet.

NISCS_PORT_SERV (A)

NISCS_PORT_SERV provides flag bits for PEDRIVER port services. Setting bits 0 and 1 (decimal value 3) enables data checking. The remaining bits are reserved for future use.

Starting with OpenVMS Version 7.3-1, you can use the SCACP command SET VC/CHECKSUMMING to specify data checking on the VCs to certain nodes. You can do this on a running system. (Refer to the SCACP documentation in this manual for more information.)

Changing the setting of NISCS_PORT_SERV, on the other hand, requires a reboot. Furthermore, this parameter applies to all virtual circuits between the node on which it is set and other nodes in the cluster.

NOAUTOCONFIG (D)

NOAUTOCONFIG controls whether all devices are automatically configured when the system boots. The default value of 0 sets the system to automatically configure all devices. Set NOAUTOCONFIG to 1 (no automatic configuration) only for debugging purposes.

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

NOCLUSTER

NOCLUSTER controls whether page read clustering is inhibited when the system boots. Set NOCLUSTER to 1 (inhibit page read clustering) only for debugging purposes.

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

NOPGFLSWP

If enabled, NOPGFLSWP disables swapping into page files.

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

NPAGECALC

NPAGECALC controls whether the system automatically calculates the initial size for nonpaged dynamic memory.

HP sets the default value of NPAGECALC to 1 only during the initial boot after an installation or upgrade. When the value of NPAGECALC is 1, the system calculates an initial value for the NPAGEVIR and NPAGEDYN system parameters. This calculated value is based on the amount of physical memory in the system.

NPAGECALC's calculations do not reduce the values of NPAGEVIR and NPAGEDYN from the values you see or set at the SYSBOOT prompt. However, NPAGECALC's calculation might increase these values.

AUTOGEN sets NPAGECALC to 0. NPAGECALC should always remain 0 after AUTOGEN has determined more refined values for the NPAGEDYN and NPAGEVIR system parameters.

NPAGEDYN (A,F,G,M)

NPAGEDYN sets the size of the nonpaged dynamic pool in bytes. This figure is rounded down to an integral number of pages. NPAGEDYN establishes the initial setting of the nonpaged pool size, but the pool size can be increased dynamically.

To set a value for this parameter, use AUTOGEN initially, and then monitor the amount of space actually used with the DCL command SHOW MEMORY/POOL/FULL.

For the benefit of OpenVMS VAX systems with limited physical memory, AUTOGEN logs a warning message in its report if NPAGEDYN exceeds 10 percent of physical memory or if NPAGEVIR exceeds 33 percent of physical memory.

AUTOGEN also limits its own calculated value for NPAGEDYN to 20 percent of physical memory and limits NPAGEVIR to 50 percent of physical memory. These calculated values are adequate for most workstations and systems with 16 or fewer megabytes of physical memory. If your system requires a larger value, you can override the AUTOGEN calculated values by setting higher values in MODPARAMS.DAT.

NPAGERAD (G)

(Alpha and I64) NPAGERAD specifies the total number of bytes of nonpaged pool that will be allocated for Resource Affinity Domains (RADs) other than the base RAD. For platforms that have no RADs, NPAGERAD is ignored. Notice that NPAGEDYN specifies the total amount of nonpaged pool for all RADs.

Also notice that the OpenVMS system might round the specified values higher to an even number of pages for each RAD, which prevents the base RAD from having too little nonpaged pool. For example, if the hardware is an AlphaServer GS160 with 4 RADs: 


NPAGEDYN = 6291456 bytes
NPAGERAD = 2097152 bytes

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