HP OpenVMS Alpha Version 8.3 and HP OpenVMS Version
•Memory errors. These can be unrecoverable (hard) errors or recoverable (soft) errors. The system ex- amines memory at startup time and does not use any bad pages. During system operation, the system cor- rects all
•Correctible memory errors. A primary cause of these correctible memory errors is alpha particle radi- ation. On some processors, when correctible mem- ory errors occur, the memory controller corrects only the data returned to the CPU or I/O controller. The actual data in memory is left with the error intact. Subsequent read operations cause correction cycles to occur and, in most cases, an interrupt to report the error. On many of these processors, OpenVMS monitors the occurrence of correctible memory errors and, in almost all cases, is able to remove the error condition by rewriting the data in memory. Rewrit- ing the data causes the data to be corrected in that memory location.
Other failures include:
•Operating system errors
•User errors
•I/O errors
The system logs all processor errors, all operating system errors detected through internal consistency checks, all
If the system is shut down because of an unrecoverable hardware or software error, a dump of physical mem- ory is written. The dump includes the contents of the processor registers. The OpenVMS System Dump An- alyzer (SDA) utility is provided for analyzing memory dumps.
Input/Output
The QIO system service and other related I/O services provide a direct interface to the operating system’s I/O routines. These services are available from within most OpenVMS programming languages and can be used to perform
Device drivers execute I/O instructions to transfer data to and from a device and to communicate directly with an I/O device. Each type of I/O device requires its own driver. HP supplies drivers for all devices supported by the OpenVMS operating system and provides QIO system service routines to access the special features available in many of these devices.
OpenVMS supports a variety of disk and tape periph- eral devices, as well as terminals, networks, and mail- boxes (virtual devices for interprocess communication), and more general I/O devices.
I/O Performance Features
Fast I/O provides a suite of additional system services that applications can use to improve I/O throughput. The fast I/O services minimize the CPU resources required to perform I/O.
Fast Path provides a streamlined mainline code path through the I/O subsystem to improve both uniproces- sor and multiprocessor I/O performance. On multipro- cessor systems, Fast Path allows all CPU processing for specific I/O adapters to be handled by a specific CPU. This can significantly lower the demands on the primary CPU and increase the I/O throughput on multiproces- sor systems with multiple I/O ports. No user application changes are needed to take advantage of Fast Path. Fast Path can be utilized by the $QIO system service or the Fast I/O services.
Extended File Cache (XFC)
The Extended File Cache (XFC) is a virtual block data cache provided with OpenVMS Alpha and OpenVMS for Integrity servers. Similar to the Virtual I/O Cache, the XFC is a clusterwide, file system data cache. Both file system data caches are compatible and coexist in the OpenVMS Cluster.
The XFC improves I/O performance with the following features that are not available with the virtual I/O cache:
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•Automatic resizing of the cache
•Larger maximum cache size
•No limit on the number of closed files that can be cached
•Control over the maximum size of I/O that can be cached
•Control over whether cache memory is static or dy- namic
Virtual I/O Cache (Alpha only)
OpenVMS Alpha provides a standalone or clusterwide,
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