User manual

Miscellaneous Notes

see additional processors added to the system and will under-collect performance data, at best,

or may even crash.

On a 32-processor system MONITOR utility collects and displays load information only for first

31 processors. While 32nd processor is there and is performing system workload, MONITOR will

not see it and will not collect load information for it.

ANALYZE /SYSTEM

Similarly, if SDA utility is running on a live system while VSMP LOAD command is being executed,

restart SDA after completing VSMP LOAD to let it see additional CPUs added to the system.

Watchpoint utility and WPDRIVER

Use of WPDRIVER is unsupported in the current release of VAX MP when multiple processors

are active. It is safe to use WPDRIVER on VAX MP when only one processor is active, but not

when multiple processors are active.

WPDRIVER references WHAMI macro. This macro is not aware of VAX MP multiprocessing

capabilities and will incorrectly treat it as uniprocessor MicroVAX 3900, resulting in improper

operation and possible system crashes. It may be possible in the future to provide a patch for

WPDRIVER enabling its use in multiprocessor mode on VAX MP, should there be a need for such

use that justifies required effort.

Running cluster

When running VAX software simulator, whether uniprocessor or multiprocessor, as a member of

a cluster, it is prudent to adjust the values of SYSGEN parameters TIMVCFAIL and

RECNXINTERVAL across the cluster. TIMVCFAIL governs timeout interval for cluster virtual

circuits. If a cluster member does not receive acknowledgement from another member within

TIMVCFAIL interval, it considers the circuit broken and initiates reconnection attempt that lasts

up to maximum interval indicated by RECNXINTERVAL. Once RECNXINTERVAL expires, remaining

nodes abandon attempt to reestablish connection with the lost node and proceed to rebuild the

cluster without the lost node or nodes.

Unlike with silicon VAX, simulator-based VAX (or Alpha) node response can be delayed by

simulator’s thread preemption due to host system load, spin-up of disks previously spun down

according to host power saving policy, intervention of antivirus software and so on. To prevent

false circuit breakdown induced by these factors, it is prudent to increase the value of

TIMVCFAIL from default of 1600 (corresponding to 16 seconds) to 3000 (corresponding to 30

seconds). There is no point in further increasing TIMVCFAIL beyond the value 3000 as NI port

This issue can potentially be fixed later by converting resident part of VSMP to SYSMAN SYS_LOADABLE image,

however that would present its own inconveniences.