Datasheet

4.1 Control/Sense Commands
C141-C008 4-49
"1": This enables the write cache.
Write data remains in the buffer memory, the cache is made the object even
for a read command, and when all of the write data has been received,
"GOOD" status is reported without disconnecting.
Sequential writing is performed without waiting for rotation.
"0": This prohibits operation of the write cache function.
Write data remains in the buffer memory, the cache is not made the object
even for a read command, and as soon as all the data has been written to the
disk, "GOOD" status is reported.
d. SIZE (size enable) (not supported)
"1": Divides the data buffer in accordance with the value specified for the
cache segment size (bytes 14, 15).
"0": Divides the data buffer in accordance with the value specified for the
number of cache segments (byte 13).
This bit cannot be changed. The IDD disregards the specification in this bit
and operates according to the "Default" value (= "0").
e. DISC (discontinuity)
"1": Even if a track switch occurs during Look-Ahead, the Look-Ahead
operation continues without interruption.
"0": Look-Ahead is terminated at the point where track switch occurs during
Look-Ahead.
This bit cannot be changed. The IDD disregards the specification in this bit
and operates according to the "Default" value (= "1").
f. IC (initiator control enable)
"1": Dividing of cache segments is according to the SIZE bit specification.
"0": Dividing of the cache segments is performed by an algorithm that is inherent
in the IDD.
This bit can be changed, and its operation is as specified.
g. Demand read retention priority (not supported)
This field advises the device server the retention priority to assign for data
read into the cache that has also been transferred from the logical unit to the
application client.
The IDD are not supported this field. Thus, the IDD disregards the
specification in this field.
"F": Data put into the cache via a READ command was not replaced if there
is other data in the cache that was placed into the cache by other means
and it may be replaced.