OpenVMS Cluster Systems - OpenVMS Systems - HP

Table A–1 (Cont.) Adjustable Cluster System Parameters
Parameter Description
Cluster System Parameters
A.1 Values for Alpha and VAX Computers
‡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 (disks
only)
Enables MSCP served disks 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 are used in the formation of additional multipath sets.
MPDEV_REMOTE is enabled by default. However, setting this parameter to
OFF has no 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.
MSCP_BUFFER 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 the MSCP server’s local buffer area.
MSCP_CMD_TMO Specifies 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.
An MSCP_CMD_TMO 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, 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 Specifies the number of outstanding I/O requests that can be active from one
client system.
MSCP_LOAD Controls whether the MSCP server is loaded. Specify 1 to load the server,
and use the default CPU load rating. A value greater than 1 loads the server
and uses this value as a constant load rating. By default, the value is set to
0 and the server is not loaded.
‡Alpha specific
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Cluster System Parameters A–5