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SCSI Description
5-54 Maxtor Atlas 10K III
Caching Page-(Page 8)
PS 1
Parameters Savable. This bit is only used with the MODE SENSE com-
mand. A returned value of 1 indicates that the target is capable of saving
the page in a non-volatile, vendor-specific location. Bit reserved with
MODE SELECT command.
WCE 1
Write Cache Enable. The default value of 1 enables write-back caching
when processing a WRITE command. When set to 0 the drive returns a
GOOD status and COMMAND COMPLETE only after successfully writing
all the data to the media.
When WCE = 1, write-back caching is enabled while processing a WRITE
command. The drive returns a GOOD status and COMMAND COMPLETE
only after fetching the data from the initiator and placing it in the drive’s
cache memory.
Note: For maximum data integrity, it is strongly recommended
that when
WCE is set to 1, the Read-Write Error Recovery Page (01h) fields be set
as follows:
• AWRE to 1
• RC to 0
• DCR to 0
• Correction Span set to 170
• Head Offset to 0
• Servo Offset to 0
MF 0
Multiplication Factor (value must be 0). The drive interprets the minimum
and maximum pre-fetch fields values in terms of the number of logical
blocks for each of the respective types of prefetch.
RCD 0
Read Cache Disable. The default value of 0 enables the read cache capa-
bility and allows the drive to use cache-resident data or medium data to
satisfy a READ command.
When the value is 1, read caching is disabled and the data returned in re-
sponse to a READ command is fetched from the medium and not from the
drive’s cache memory.
Demand Read
Retention
Priority
0
This field advises the drive on the retention priority to assign data read into
the cache that has also been transferred from the drive to the initiator.
Demand Write
Retention
Priority
0
This field advises the drive on the retention priority to assign data written
into the cache that has also been transferred from the cache memory to
the medium.
Disable
Pre-Fetch
FFFFh
This field specifies the selective disabling of anticipatory pre-fetch
Transfer
Length
on long transfer lengths. The value in this field is compared to the number
of sectors requested by the current READ command. If the number of sec-
tors is greater the than the value specified, anticipatory pre-fetch is not
performed for the command. When 0, anticipatory pre-fetch is disabled.
Minimum
Pre-fetch
0
This field indicates the number of sectors that are to be pre-fetched. See
also MF.
Maximum
Pre-fetch
0421h
This field indicates the maximum amount of data to pre-fetch into the
cache as a result of one READ command.