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CHEETAH 15K.7 SAS PRODUCT MANUAL, REV. F 9
4.2.3 General performance characteristics
Sustainable disk transfer rate*:
Minimum 122 Mbytes/sec (typical)
Maximum 204 Mbytes/sec (typical)
SAS Interface maximum instantaneous transfer rate 600 Mbytes/sec* per port
Logical block sizes
Default is 512-byte data blocks
Sector sizes variable to 512, 520, and 528 kbytes.
Read/write consecutive sectors on a track Yes
Flaw reallocation performance impact (for flaws reallocated at format time using
the spare sectors per sparing zone reallocation scheme.)
Negligible
Average rotational latency 2.0 msec
*Assumes system ability to support the rates listed and no cable loss.
1 MB/sec = 1,000,000 bytes/sec
4.3 START/STOP TIME
The drive accepts the commands listed in the SAS Interface Manual less than 3 seconds after DC power has been applied.
If the drive receives a NOTIFY (ENABLE SPINUP) primitive through either port and has not received a START STOP UNIT
command with the START bit equal to 0, the drive becomes ready for normal operations within 20 seconds (excluding the
error recovery procedure).
If the drive receives a START STOP UNIT command with the START bit equal to 0 before receiving a NOTIFY (ENABLE
SPINUP) primitive, the drive waits for a START STOP UNIT command with the START bit equal to 1. After receiving a
START STOP UNIT command with the START bit equal to 1, the drive waits for a NOTIFY (ENABLE SPINUP) primitive.
After receiving a NOTIFY (ENABLE SPINUP) primitive through either port, the drive becomes ready for normal operations
within 20 seconds (excluding the error recovery procedure).
If the drive receives a START STOP UNIT command with the START bit and IMMED bit equal to 1 and does not receive a
NOTIFY (ENABLE SPINUP) primitive within 5 seconds, the drive fails the START STOP UNIT command.
The START STOP UNIT command may be used to command the drive to stop the spindle. Stop time is 30 seconds
(maximum) from removal of DC power. There is no power control switch on the drive.
4.4 PREFETCH/MULTI-SEGMENTED CACHE CONTROL
The drive provides a prefetch (read look-ahead) and multi-segmented cache control algorithms that in many cases can
enhance system performance. Cache refers to the drive buffer storage space when it is used in cache operations. To select
this feature, the host sends the Mode Select command with the proper values in the applicable bytes in page 08h. Prefetch
and cache operations are independent features from the standpoint that each is enabled and disabled independently using
the Mode Select command; however, in actual operation, the prefetch feature overlaps cache operation somewhat as
described in sections 4.5.1 and 4.5.2.
All default cache and prefetch mode parameter values (Mode Page 08h) for standard OEM versions of this drive family are
given in Section 11.3.2.1.