Hitachi HUS154530VLF400 User Manual

                                    

Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification

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The caching parameters page defines parameters that affect the use of the cache.

•   IC  (Initiator Control) bit of one specifies that the drive will honor the following parameters to control cache 

segmentation and pre-fetch:  SIZE, FSW, LBCSS, Number of Cache Segments, Cache Segment Size.  The drive will 
never pre-fetch less data than specified by ABPF, MF, Demand Read Retention Priority, Write Retention Priority, 
Disable Pre-fetch Transfer Length, Minimum Pre-fetch, Maximum Pre-fetch, and Maximum Pre-fetch Ceiling, but 
may pre-fetch more based on internal cache algorithms.  When the IC bit is set to zero, all the parameters listed above 
are ignored, and an internal caching algorithm is used. 

• ABPF (Abort Pre-fetch) bit of one, with DRA set to zero, causes the drive to abort the pre-fetch upon receipt of a new 

command.  ABPF set to one takes precedence over Minimum Pre-fetch.  When ABPF is zero, with DRA set to zero, 
the termination of any active pre-fetch is dependant upon the other parameters in this page.

• CAP (Caching Analysis Permitted) is not supported and is ignored.  The IC bit can be used to enable or disable adaptive 

caching.

• DISC (Discontinuity) is not supported and is ignored.  Pre-fetch operations will continue across cylinders, within the 

limits of other caching parameters on this page.

• SIZE (Size Enable) bit when set to one indicates that the Cache Segment Size is to be used to control caching segmenta-

tion. When SIZE is set to zero, the Initiator requests that the Number of Cache Segments is to be used to control cach-
ing segmentation.

• WCE (Write Cache Enable) bit when set at zero indicates that the drive must issue Good status for WRITE (6) or 

WRITE (10) command only after successfully writing the data to the media. When the WCE bit is set to one, the 
drive may issue Good status for a WRITE (6) or WRITE (10) command after successfully receiving the data but 
before writing it to the media. When WCE = 1, the drive operates as if AWRE = 1.