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

Negligible

the spare sectors per sparing zone reallocation scheme.)

 

 

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

 

 

4.3START/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.

4.4PREFETCH/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.

CHEETAH 15K.7 SAS PRODUCT MANUAL, REV. F

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Seagate ST3300657SS manual General performance characteristics, START/STOP Time, PREFETCH/MULTI-SEGMENTED Cache Control