Seagate Medalist 2160N (ST52160N), Руководство по эксплуатации продукта

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drive terminates prefetching whenever another command
is ready to be executed. If the minimum prefetch equals
the maximum prefetch, the drive prefetches the same
number of blocks regardless of whether there are com-
mands pending.
Bytes 8–9
The
maximum prefetch field specifies the maximum num-
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 that is set to 1
indicates that multiple block writes are to be transferred
over the SCSI bus and written to the media in an ascend-
ing, 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 is 0, the
drive can continue reading logical blocks into the buffer
beyond the addressed logical blocks.
Byte 13 The number of cache segments field determines the
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.
112 Medalist Pro 2160N/2160WC Product Manual, Rev. A