User Guide

234 Spheras Storage Director Installation & User Guide
Warm Swap
The exchange of a defective disk with a working disk while
power is maintained to the system, but I/O operations have
ceased.
Web
A number of computers, servers, or networks linked
together in a matrix.
Write-Back Cache
A caching strategy whereby write operations result in a
completion signal being sent to the host operating system
as soon as the cache (not the disk drive) receives the data to
be written. The target disk drive will receive the data at a
more appropriate time in order to increase controller
performance. An optional cache battery backup can be
used to protect against data loss as a result of a power
failure or system crash.
Write-Through Cache
A caching strategy whereby data is written to the SCSI
drive before a completion status is returned to the host
operating system. This caching strategy is considered more
secure, since a power failure will be less likely to cause
loss of data. However, a write through cache results in a
slightly lower performance.