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232 Fibre Channel Interface Manual, Rev. D
If the Non-Cache Segment Size field = 0
or
the Non-Cache Segment Size field value + Cache Segment Size field > buffer size,
then
the vendor determines the cache function.
Number of Cache Segments
The number of segments into which the host requests the drive divide the cache.
Page Code
08h Caching Parameters page for Mode Sense/Mode Select page code.
Page Length
12h The length of the Caching Parameters page (in bytes). If the allocation length is too small to transfer all of the page,
the page length is not adjusted to reflect the truncation.
PS (Parameter Savable)
This bit is not used with the Mode Select command.
1 Page 01h parameter data is savable and the bit function is directly changeable by an initiator (see Mode Select
command).
0 This bit function is not directly changeable by an initiator, a value of 1 means the bit function is directly changeable
by an initiator. See the individual drive’s Product Manual, Volume 1, for changeable values.
RCD (Read Cache Disable)
0 SCSI Read commands may access the cache or the media.
1 SCSI Read commands must access the media. Data cannot come from the cache.
SIZE (Size Enable)
For Seagate drives covered by this manual, this bit is always zero (0).
1 The Cache Segment Size is to be used to control caching segmentation.
0 The Initiator requests that the Number of Cache Segments is to be used to control caching segmentation.
WCE (Write Cache Enable)
0 SCSI Write commands will not return Completion Status until all data has been written to the media.
1 SCSI Write commands may return Completion Status as soon as all data has been received from the host.
Write Retention Priority
The cache replacement algorithm does distinguish between retention in the cache of host-requested data and prefetch
data. Therefore, this half byte is always 0.
Note. In addition to the caching control provided by the Caching Mode page, some 10-byte commands contain control
bits DPO and FUA—the intent of which is to override the cache page control bits.
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