Compaq StorageWorks HSG60 ACS Solution Software V8.6 for Compaq Tru64 UNIX Installation and Configuration Guide

Glossary–20 HSG60 ACS Solution Software Version 8.6 for Compaq Tru64 UNIX Installation and Configuration
Guide
write-through
caching
A cache management method used to decrease the subsystem response time to
a read. This method allows the controller to satisfy the request from the cache
memory rather than from the disk drives.
write hole The period of time in a RAID level 1 or RAID level 5 write operation when an
opportunity emerges for undetectable RAIDset data corruption. Write holes
occur under conditions such as power outages, where the writing of multiple
members can be abruptly interrupted. A battery backed-up cache design
eliminates the write hole because data is preserved in cache and unsuccessful
write operations can be retried.
write-through
cache
A cache management technique for retaining host write requests in read cache.
When the host requests a write operation, the controller writes data directly to
the storage device. This technique allows the controller to complete some read
requests from the cache, greatly improving the response time to retrieve data.
The operation is complete only after the data to be written is received by the
target storage device.
This cache management method may update, invalidate, or delete data from
the cache memory accordingly, to ensure that the cache contains the most
current data.