Seagate ST3285N, Product Manual

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1.6 Acoustics
Sound pressure is measured at idle from 1 meter above the drive top
cover.
Sound pressure, typ 34 dBA
Sound pressure, max 38 dBA
1.7 Seek time
All seek time measurements are under nominal conditions of tempera-
ture and voltage with the drive mounted horizontally. In the table below:
•
Track-to-track seek time is the average of all possible single-track
seeks in both directions.
•
Average seek time is a true statistical random average of at least 5,000
measurements of seeks in both directions between random cylinders,
less overhead.
•
Full-stroke seek time is one-half the time needed to seek from logical
block address zero (LBA 0) to the maximum LBA and back to LBA 0.
Track-to-track
seek time Average
seek time Full-stroke
seek time Average
latency
3.5 msec typ
4.0 msec max 12.0 msec typ
14.0 msec max 30.0 msec typ
32.0 msec max 6.67 msec
Note. Host overhead varies between systems and cannot be specified.
Drive internal overhead is measured by issuing a no-motion seek.
Drive overhead is typically less than 1.0 msec.
1.7.1 Read look-ahead and caching
The drive uses algorithms that improve seek performance by storing data
in a buffer and processing it at a more convenient time. Three methods
are employed: read look-ahead, read caching and write caching. These
are described in Appendix C.5.
1.7.2 Thermal compensation
The thermal compensation feature compensates for position offset of the
selected head due to variations in temperature. The drive automatically
performs thermal compensation during startup and every 2 minutes
thereafter.
ST3655 Family SCSI Drives Product Manual, Rev. A 3