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Idle Read After Write

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10.7 Idle Read After Write Idle Read After Write (IRAW) utilizes idle time to verify the integrity of recently written data. During idle periods, no active system requests, the drive reads recently written data from the media and compares it to valid write command data resident in the drives data buffer. Any sectors that fail the comparison result in the invocation of a rewrite and auto-reallocation process. The process attempts to rewrite the data to the original location. If a verification of this rewrite fails, the sector is re-mapped to a spare location. 48 Constellation ES Series SAS Product Manual, Rev. F

Section	Page
1.0 Seagate Technology support services	9
2.0 Scope	10
3.0 Applicable standards and reference documentation	11
3.1 Standards	11
3.1.1 Electromagnetic compatibility	11
3.1.1.1 Electromagnetic susceptibility	11
3.1.2 Electromagnetic compliance	12
3.1.3 European Union Restriction of Hazardous Substances (RoHS)	13
3.2 Reference documents	13
4.0 General description	14
4.1 Standard features	15
4.2 Media description	15
4.3 Performance	16
4.4 Reliability	16
4.5 Formatted capacities	16
4.6 Programmable drive capacity	16
4.7 Factory-installed options	17
5.0 Performance characteristics	18
5.1 Internal drive characteristics	18
5.2 Seek performance characteristics	18
5.2.1 Access time	18
5.2.2 Format command execution time for 512-byte sectors (minutes)	19
5.2.3 General performance characteristics	19
5.3 Start/stop time	19
5.4 Prefetch/multi-segmented cache control	20
5.5 Cache operation	20
5.5.1 Caching write data	21
5.5.2 Prefetch operation	21
6.0 Reliability specifications	22
6.1 Error rates	22
6.1.1 Recoverable Errors	22
6.1.2 Unrecoverable Errors	22
6.1.3 Seek errors	23
6.1.4 Interface errors	23
6.2 Reliability and service	23
6.2.1 Annualized Failure Rate (AFR) and Mean Time Between Failure (MTBF)	23
6.2.2 Preventive maintenance	23
6.2.3 Hot plugging the drive	23
6.2.4 S.M.A.R.T.	24
6.2.5 Thermal monitor	25
6.2.6 Drive Self Test (DST)	26
6.2.6.1 DST failure definition	26
6.2.6.2 Implementation	26
6.2.7 Product warranty	28
7.0 Physical/electrical specifications	29
7.1 PowerChoiceTM power management	29
7.1.1 PowerChoice reporting methods	30
7.2 AC power requirements	30
7.3 DC power requirements	30
7.3.1 Conducted noise immunity	34
7.3.2 Power sequencing	34
7.3.3 Current profiles	35
7.4 Power dissipation	38
7.5 Environmental limits	44
7.5.1 Temperature	44
7.5.2 Relative humidity	44
7.5.3 Effective altitude (sea level)	45
7.5.4 Shock and vibration	45
7.5.4.1 Shock	45
7.5.4.2 Vibration	46
7.5.5 Acoustics	47
7.5.6 Air cleanliness	47
7.5.7 Corrosive environment	47
7.5.8 Electromagnetic susceptibility	47
7.6 Mechanical specifications	48
8.0 About FIPS	49
9.0 About self-encrypting drives	50
9.1 Data encryption	50
9.2 Controlled access	50
9.2.1 Admin SP	50
9.2.2 Locking SP	51
9.2.3 Default password	51
9.3 Random number generator (RNG)	51
9.4 Drive locking	51
9.5 Data bands	51
9.6 Cryptographic erase	52
9.7 Authenticated firmware download	52
9.8 Power requirements	52
9.9 Supported commands	52
10.0 Defect and error management	53
10.1 Drive internal defects/errors	53
10.2 Drive error recovery procedures	53
10.3 SAS system errors	54
10.4 Background Media Scan	55
10.5 Media Pre-Scan	55
10.6 Deferred Auto-Reallocation	55
10.7 Idle Read After Write	56
11.0 Installation	57
11.1 Drive orientation	57
11.2 Cooling	58
11.3 Drive mounting	59
11.4 Grounding	59
12.0 Interface requirements	60
12.1 SAS features	60
12.1.1 task management functions	60
12.1.2 task management responses	60
12.2 Dual port support	61
12.3 SCSI commands supported	62
12.3.1 Inquiry data	66
12.3.2 Mode Sense data	66
12.4 Miscellaneous operating features and conditions	71
12.4.1 SAS physical interface	72
12.4.2 Physical characteristics	75
12.4.3 Connector requirements	75
12.4.4 Electrical description	75
12.4.5 Pin descriptions	75
12.4.6 SAS transmitters and receivers	76
12.4.7 Power	76
12.5 Signal characteristics	76
12.5.1 Ready LED Out	76
12.5.2 Differential signals	77
12.6 SAS-2 Specification Compliance	77
12.7 Additional information	77
Numerics	79
A	79
B	79
C	79
D	79
E	80
F	80
G	80
H	80
I	80
J	80
K	80
L	81
M	81
N	81
O	81
P	81
Q	81
R	82
S	82
T	82
U	82
V	83
W	83

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Constellation ES Series SAS Product Manual, Rev. F

10.7

Idle Read After Write

Idle Read After Write (IRAW) utilizes idle time to verify the integrity of recently written data. During idle periods,

no active system requests, the drive reads recently written data from the media and compares it to valid write

command data resident in the drives data buffer. Any sectors that fail the comparison result in the invocation of

a rewrite and auto-reallocation process. The process attempts to rewrite the data to the original location. If a

verification of this rewrite fails, the sector is re-mapped to a spare location.