Seagate ST35000415SS Performance characteristics, Internal drive characteristics, Access time

4.0Performance characteristics

This section provides detailed information concerning performance-related characteristics and features of Con- stellation ES drives.

4.1Internal drive characteristics

	ST32000444SS	ST31000424SS	ST3500414SS
	ST32000445SS	ST31000425SS	ST3500415SS
Drive capacity	2000	1000	500	GB (formatted, rounded off value)
Read/write data heads	8	4	2
Bytes per track	1,012,608	1,012,608	1,012,608	Bytes (average, rounded off values)
Bytes per surface	250,000	250,000	250,000	MB (unformatted, rounded off value)
Tracks per surface (total)	248,600	248,600	248,600	Tracks (user accessible)
Tracks per inch	237,000	237,000	237,000	TPI (average)
Peak bits per inch	1,515,000	1,515,000	1,515,000	BPI
Areal density	347	347	347	Gb/in2
Internal data rate	95 - 212	95 - 212	95 - 212	MB/s (variable with zone)
Disc rotation speed	7200	7200	7200	rpm
Avg rotational latency	4.16	4.16	4.16	ms

4.2Seek performance characteristics

See Section 10.4.1, "SAS physical interface" on page 63 and the SAS Interface Manual (part number 100293071) for additional timing details.

4.2.1Access time

		Not including controller overhead1, 2 (ms)		Including controller overhead1, 2 (ms)
		Read	Write	Read	Write
Average	Typical3,4	8.3	9.3	8.5	9.5
Single track	Typical3,4	0.5	0.8	0.7	1.0
Full stroke	Typical3,4	18	19	18.2	19.2

1.Execution time measured from receipt of the Command to the Response.

2.Assumes no errors and no sector has been relocated.

3.Typical access times are measured under nominal conditions of temperature, voltage, and horizontal orientation as measured on a representative sample of drives.

4.Access time = controller overhead + average seek time and applies to all data transfer commands. Access to data = access time + latency time.

ConstellationES Series SAS Product Manual, Rev. D 9