Seagate ST3285N, Product Manual

Page: 113 / 151

Bit
Byte
7 6 5 4 3 2 1 0
13 Number of cache segments
default 0 0 0 0 0 0 0 1
changeable 1 1 1 1 1 1 1 1
14–15 (default) Cache segment size (0000
H
)
changeable 0000
H
16 (default) Reserved (00
H
)
changeable 00
H
17–19 (default) Noncache segment size (000000
H
)
changeable 000000
H
Byte 2 When the Initiator Control (IC) bit is 1, the drive uses either the
number of cache segments field or the cache segment size field,
as determined by the SIZE bit (bit 3), to control the caching
algorithm. When the IC bit is 0, the drive uses its own algorithm
to control caching.
When the Abort Prefetch (ABPF) bit is 0, the drive controls
completion of prefetch. See the description for the DISC bit,
below. This is the default value and it is not changeable.
When the Caching Analysis Permitted (CAP) bit is 0, caching
analysis is disabled to reduce overhead time or to prevent
operations that are not pertinent from impacting tuning values.
When the CAP bit is 1, caching analysis is enabled.
When the
Discontinuity (DISC) bit is 1, the drive may prefetch
across cylinder boundaries, where head seeks consume addi-
tional processing time. This is the default value and it is not
changeable.
When the Size Enable (SIZE) bit is 0, the drive uses the number
of cache segments field to control caching segmentation. When
the SIZE bit is 1, the drive uses the cache segment size field to
control caching segmentation.
When the
Write Cache Enable (WCE) bit is 0, the drive returns
a good status for a Write command after successfully writing all
the data to the media. When the WCE bit is 1, the drive returns
a good status for a Write command after successfully receiving
the data and before writing it to the media.
ST3655 Family SCSI Drives Product Manual, Rev. A 103