Seagate ST12450W, Product Manual

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ST12450W/WD Product Manual, Rev. A 11
5.0 Performance characteristics
This section provides performance-related characteristics and features of
Barracuda 2, 2HP drives.
5.1 Internal drive characteristics
Drive capacity, Mbytes unformatted 2,437
Read/write data heads, maximum (physical) 18
Read/write data heads, maximum (logical) 9
Bytes per track, average bytes 99,536
Bytes per surface, Mbytes unformatted 271.4
Cylinders/tracks per surface, user accessible 2,710
Tracks per inch 3,047
Bits per inch 52,187
Servo heads 1
Internal data rate per physical head, Mbits/sec, 34.3 to 56.5
variable with zone
Internal data rate per logical head, Mbits/sec, 68.6 to 113.0
variable with zone
Disc rotation speed 7,200
±
0.5%
Average rotational latency, msec 4.17
5.2 SCSI seek performance characteristics
All performance characteristics assume that automatic adaptive thermal
compensation is not in process when the drive receives the SCSI command.
Automatic adaptive thermal compensation will not interrupt an active SCSI
command. If adaptive thermal compensation is in process when a SCSI
command is received, the command is queued until the compensation for
the specific head being compensated completes. When compensation
completes for the specific head being compensated, the first queued SCSI
command executes. When execution of the first queued command is
complete, the drive continues the compensation for the remaining head(s).
The above procedure continues until compensation for all heads has
completed, or until 10 minutes have elapsed. The drive initiates an auto-
matic adaptive thermal compensation cycle once on power-up before
completing its initialization sequence and then once after 1 minute from the
end of initialization. After this, the drive initiates an automatic adaptive
thermal compensation cycle approximately once every 10 minutes. Non-
interruptible automatic thermal compensation occurs at other times but
should be transparent to the user (e.g., during format, Re-zero command,
at spindle-up, during read-error recovery, and during reassign-block func-
tions). You can use the Re-zero command to reset the thermal compensa-
tion timer back to its start so that the host knows when the interruption for
thermal compensation will occur.