Seagate MEDALIST 1080SL Product Manual page 102

92 Medalist 1080sl SCSI Product Manual, August 1995
The maximum prefetch field specifies the maximum num-
Bytes 8–9
ber of blocks the drive prefetches during a Read com-
mand if there are no other commands pending. The
maximum prefetch field represents the maximum amount
of data to prefetch into the cache for any single Read
command.
Bytes 10–11 The maximum prefetch ceiling field should be equal to the
maximum prefetch field. The maximum prefetch ceiling
and maximum prefetch fields are the same if the MF bit
is 0.
Byte 12 The force sequential write (FSW) bit set to one indicates
that multiple block writes are to be transferred over the
SCSI bus and written to the media in an ascending,
sequential, logical block order.
When the disable read-ahead (DRA) bit is 1, the drive
does not read into the buffer any logical blocks beyond
the addressed logical blocks. When the DRA bit equals 0,
the drive can continue reading logical blocks into the
buffer beyond the addressed logical blocks.
The number of cache segments field determines the
Byte 13
number of segments into which the cache should be
divided. Valid values are 1, 2, 4, 8, 16 and 32.
Bytes 14–15 The cache segment size field indicates the segment size
in bytes. The cache segment size field is valid only when
the SIZE bit is 1.
Byte 16 Reserved
Bytes 17–19 The noncache segment size field always contains zeros.
This means that the entire buffer is available for caching.