Seagate ST300MP0004 Savvio 15K SAS Product Manual - Page 21

Savvio 15K SAS Product Manual, Rev. B

13

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.

All default cache and prefetch mode parameter values (Mode Page 08h) for standard OEM versions of this

drive family are given in Table 9.

4.5

Cache operation

Note.

Refer to the

SAS Interface Manual

for more detail concerning the cache bits.

Of the 16 Mbytes physical buffer space in the drive, approximately 13,000 kbytes can be used as a cache. The

buffer is divided into logical segments from which data is read and to which data is written.

The drive keeps track of the logical block addresses of the data stored in each segment of the buffer. If the

cache is enabled (see RCD bit in the

SAS Interface Manual

), data requested by the host with a read command

is retrieved from the buffer, if possible, before any disc access is initiated. If cache operation is not enabled, the

buffer is still used, but only as circular buffer segments during disc medium read operations (disregarding

Prefetch operation for the moment). That is, the drive does not check in the buffer segments for the requested

read data, but goes directly to the medium to retrieve it. The retrieved data merely passes through some buffer

segment on the way to the host. All data transfers to the host are in accordance with buffer-full ratio rules. See

the explanation provided with the information about Mode Page 02h (disconnect/reconnect control) in the

SAS

Interface Manual

.

The following is a simplified description of the prefetch/cache operation:

Case A

—read command is received and all of the requested logical blocks are already in the cache:

1.

Drive transfers the requested logical blocks to the initiator.

Case B

—A Read command requests data, and at least one requested logical block is not in any segment of

the cache:

Section	Page
Figure 1. Typical ST973451SS current profile 25	7
Figure 2. Typical ST936751SS current profile 26	7
Figure 3. ST973451SS (3 Gbit) DC current and power vs. input/output operations per second 27	7
Figure 4. ST973451SS (1.5 Gbit) DC current and power vs. input/output operations per second 27	7
Figure 5. ST936751SS (3 Gbit) DC current and power vs. input/output operations per second 28	7
Figure 6. ST936751SS (1.5 Gbit) DC current and power vs. input/output operations per second 28	7
Figure 7. Location of the HDA temperature check point 29	7
Figure 8. Recommended mounting 31	7
Figure 9. Mounting configuration dimensions 34	7
Figure 10. Physical interface 39	7
Figure 11. Air flow 40	7
Figure 12. Physical interface 54	7
Figure 13. SAS device plug dimensions 55	7
Figure 14. SAS device plug dimensions (detail) 56	7
Figure 15. SAS transmitters and receivers 58	7
Figure 16. Receive eye mask 60	7
Figure 17. Reveive tolerance eye mask 61	7
Figure 18. Sinusoidal jitter mask 62	7
Figure 19. Compliance interconnect test load 67	7
Figure 20. Zero-length test load 68	7
Figure 21. ISI loss example at 3.0 Gbps 68	7
Figure 22. ISI loss example at 1.5 Gbps 68	7
1.0 Scope	9
2.0 Applicable standards and reference documentation	11
2.1 Standards	11
2.1.1 Electromagnetic compatibility	11
2.1.1.1 Electromagnetic susceptibility	11
2.1.2 Electromagnetic compliance	12
2.1.3 European Union Restriction of Hazardous Substances (RoHS)	13
2.2 Reference documents	13
3.0 General description	15
3.1 Standard features	16
3.2 Media description	16
3.3 Performance	16
3.4 Reliability	17
3.5 Formatted capacities	17
3.6 Programmable drive capacity	17
3.7 Factory-installed accessories	17
3.8 Options	18
4.0 Performance characteristics	19
4.1 Internal drive characteristics	19
4.2 Seek performance characteristics	19
4.2.1 Access time (Gen 2.0 LP data)	19
4.2.2 Format command execution time	20
4.2.3 General performance characteristics	20
4.3 Start/stop time	21
4.4 Prefetch/multi-segmented cache control	21
4.5 Cache operation	21
4.5.1 Caching write data	22
4.5.2 Prefetch operation	22
5.0 Reliability specifications	23
5.1 Error rates	23
5.1.1 Recoverable Errors	23
5.1.2 Unrecoverable Errors	23
5.1.3 Seek errors	24
5.1.4 Interface errors	24
5.2 Reliability and service	24
5.2.1 Annualized Failure Rate (AFR) and Mean Time Between Failure (MTBF)	24
5.2.2 Preventive maintenance	24
5.2.3 Hot plugging the drive	24
5.2.4 S.M.A.R.T.	25
5.2.5 Thermal monitor	26
5.2.6 Drive Self Test (DST)	26
5.2.6.1 DST failure definition	27
5.2.6.2 Implementation	27
5.2.6.2.1 State of the drive prior to testing	27
5.2.6.2.2 Invoking DST	27
5.2.6.2.3 Short and extended tests	27
5.2.6.2.4 Log page entries	28
5.2.6.2.5 Abort	28
5.2.7 Product warranty	28
6.0 Physical/electrical specifications	31
6.1 AC power requirements	31
6.2 DC power requirements	31
6.2.1 Conducted noise immunity	33
6.2.2 Power sequencing	33
6.2.3 Current profiles	33
6.3 Power dissipation	35
6.4 Environmental limits	37
6.4.1 Temperature	37
6.4.2 Relative humidity	37
6.4.3 Effective altitude (sea level)	38
6.4.4 Shock and vibration	38
6.4.4.1 Shock	38
6.4.4.2 Vibration	40
6.4.5 Air cleanliness	40
6.4.6 Corrosive environment	40
6.4.7 Acoustics	41
6.4.8 Electromagnetic susceptibility	41
6.5 Mechanical specifications	42
7.0 Defect and error management	43
7.1 Drive internal defects/errors	43
7.2 Drive error recovery procedures	43
7.3 SAS system errors	44
7.4 Background Media Scan	45
7.5 Media Pre-Scan	45
7.6 Deferred Auto-Reallocation	45
7.7 Idle Read After Write	46
8.0 Installation	47
8.1 Drive orientation	47
8.2 Cooling	48
8.3 Drive mounting	49
8.4 Grounding	49
9.0 Interface requirements	51
9.1 SAS features	51
9.1.1 task management functions	51
9.1.2 Task management responses	51
9.2 Dual port support	52
9.3 SCSI commands supported	53
9.3.1 Inquiry data	57
9.3.2 Mode Sense data	57
9.4 Miscellaneous operating features and conditions	61
9.4.1 SAS physical interface	62
9.4.2 Physical characteristics	65
9.4.3 Connector requirements	65
9.4.4 Electrical description	65
9.4.5 Pin descriptions	65
9.4.6 SAS transmitters and receivers	66
9.4.7 Power	67
9.5 Signal characteristics	67
9.5.1 Ready LED Out	67
9.5.2 Differential signals	67
9.5.2.1 Eye masks	68
9.5.2.1.1 Eye masks overview	68
9.5.2.1.2 Receive eye mask	68
9.5.2.1.3 Jitter tolerance masks	69
9.5.2.2 Transmitter signal characteristics	70
9.5.2.3 Receiver signal characteristics	71
9.5.2.3.1 Jitter	72
9.5.2.3.2 Receiver jitter tolerance	72
9.5.2.3.3 Compliant jitter test pattern (CJTPAT)	72
9.5.2.3.4 Impedance specifications	73
9.5.2.4 Electrical TxRx connections	74
9.5.2.4.1 Transmitter characteristics	74
9.5.2.5 Receiver characteristics	77
10.0 Seagate Technology support services	79
Numerics	81
A	81
B	81
C	81
D	81
E	81
F	82
G	82
H	82
I	82
J	82
L	82
M	82
N	83
O	83
P	83
Q	83
R	83
S	83
T	84
U	84
V	84
W	84

Seagate ST300MP0004 Savvio 15K SAS Product Manual - Page 21

Start/stop time, Prefetch/multi-segmented cache control, Cache operation

Page 21 highlights