Product manual

12
Savvio 15K SAS Product Manual, Rev. C
4.2.2 Format command execution time
Execution time measured from receipt of the last byte of the Command Descriptor Block (CDB) to the request
for a Status Byte Transfer to the Initiator (excluding connect/disconnect).
4.2.3 General performance characteristics
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 sec-
onds (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 opera-
tion, the prefetch feature overlaps cache operation somewhat as described in sections 4.5.1 and 4.5.2.
ST973451SS ST936751SS
Maximum (with verify) 52 minutes 26 minutes
Maximum (without verify) 35 minutes 18 minutes
Sustained trasfer rate 79 to 112 Mbytes/sec
SAS Interface maximum instantaneous transfer rate 300 Mbytes/sec* per port
(dual port = 600 Mbytes/sec*)
Logical block sizes
512 (default), 520, 524 and 528
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 no errors and no relocated logical blocks. Rate measured from the start of the first logical block transfer to or
from the host.