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Maxtor Atlas 10K V 5-45
NOTES:
Bytes 12 to 19 are returned only if the device operating definition is SCSI-3.
Table 5-67 Caching Page - Field Descriptions
Field
Default
Value
Description
PS 1
Parameters Savable. This bit is only used with the MODE SENSE command. 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 com-
mand.
IC 0
An initiator control (ic) enable bit set to one specifies that the device server use
the NUMBER OF CACHE
SEGMENTS field or the CACHE SEGEMENT SIZE field, dependent upon the
SIZE bit, to control the caching algorithm rather than the device server’s own
adaptive algorithm.
ABPF 0
Enable Abort Prefetch. When set, this bit requests the device abort pre-fetch
work on the receipt of a new command.Ignored by the drive
CAP 0
A caching analysis permitted (cap) bit set to one specifies that the device server
perform caching analysis during subsequent operations. A cap bit set to zero
specifies that the caching analysis be disabled to reduce overhead time or to pre-
vent non pertinent operations from impacting tuning values.
DISC 0
A discontinuity (DISC) bit set to one specifies that the device server continue
the pre-fetch across time discontinuities (e.g., across cylinders) up to the limits
of the buffer, or segment, space available for the pre-fetch. A DISC bit set to
zero specifies that pre-fetches be truncated or wrapped at time discontinuities.
ignored by drive.
Size 0
Specifies which of two fields are used to configure the cache. When Size=0, the
Number of Cache Segments field is used. When Size=1, the Cache Segment
Size field is used.
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 com-
mand. The drive returns a GOOD status and COMMAND COMPLETE only af-
ter 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 capability
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 response
to a READ command is fetched from the medium and not from the drive’s cache
memory.