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The Question is: How do I disable to d-cache on an OpenVMS Alpha System ? The Answer is :
You have not indicated why you wish to disable the Data Cache (DCache)
on your particular Alpha system.
The DCache is used to provide faster access to data, by reducing the
frequency of main system memory references. There are typically two
cache levels on an Alpha microprocessor, the primary or on-chip cache
(PCache) and the backup or off-chip cache (BCache). The on-chip PCache
is both fast and local to the processor. The off-chip BCache is
implemented on the processor module, and typically uses semiconductor
memory faster than that of the main system memory. Both the PCache
and BCache are subdivided into Instruction (ICache) and DCache, as
the patterns of references within these two tupes of data are usually
quite different.
Cache and parity errors can and often will generate error log entries,
and can potentially also generate machine check (MCHECK) crashes and
related system stability problems.
The DCache can be automatically disabled, depending on the stability
of the system hardware environment. DECevent and Compaq Analyze
will generally report the (disabled) status of the BCache with a
statement such as the following:
External Cache (Bcache) Disabled
Recurrent errors within the DCache usually point to the need to replace
the processor module, though you will want to contact your hardware
support organization for assistance and for hardware-level details on
and troubleshooting assistance with your specific Alpha hardware platform.
If you wish to perform self-maintainance of your hardware, please consider
the "Assisted Services" program referenced in the FAQ -- this program can
provide you with access to spares, repairs, diagnostics, and related.
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