Seagate Cheetah 15K.4 SAS, Product Manual

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Cheetah 15K.4 SAS Product Manual, Rev. B 11
4.0 Performance characteristics
This section provides detailed information concerning performance-related characteristics and features of
Cheetah drives.
4.1 Internal drive characteristics
ST3146854SS ST373454SS ST336754SS
Drive capacity 146.8 73.4 36.7 Gbytes (formatted, rounded off value)
Read/write data heads 8 4 2
Bytes per track 471,916 471,916 471,916 Bytes (average, rounded off values)
Bytes per surface 18,351 18,351 18,351 Mbytes (unformatted, rounded off value)
Tracks per surface (total) 50,864 50,864 50,864 Tracks (user accessible)
Tracks per inch 85,000 85,000 85,000 TPI
Peak bits per inch 628 628 628 KBPI
Internal data rate 685-1,142 685-1,142 685-1,142 Mbits/sec (variable with zone)
Disc rotation speed 15k 15k 15k rpm
Avg rotational latency 2.0 2.0 2.0 msec
4.2 Seek performance characteristics
See Section 9.4.1, "SAS physical interface" on page 57 and the SAS Interface Manual (part number
100293071) for additional timing details.
4.2.1 Access time
Not Including controller overhead
1
,
2
(msec)
1. Typical access times are measured under nominal conditions of temper-
ature, voltage, and horizontal orientation as measured on a representa-
tive sample of drives.
2. Access to data = access time + latency time.
Read Write
Average Typical 3.5 4.0
Single track Typical 0.2 0.4
Full stroke Typical 7.4 7.9