Seagate Exos X18 SAS Product Manual, Rev. D
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Performance characteristics
4.1.3
General performance characteristics
4.2
Start/stop time
Power-on to ready time is based on typical operating conditions, default full current spin-up profile, and clean shutdown prior to measurement.
To ensure a clean shutdown issue a START STOP UNIT command with the START bit set to zero and the IMMED bit set to zero, so that the device
will return status after the operation is completed.
The drive accepts the commands listed in the SAS Interface Manual less than 3 seconds after DC power has been applied.
If the drive receives a NOTIFY (ENABLE SPINUP) primitive through either port and has not received a START STOP UNIT command with the START
bit equal to 0, the drive becomes ready for normal operations within 30 seconds (excluding the error recovery procedure).
If the drive receives a START STOP UNIT command with the START bit equal to 0 before receiving a NOTIFY (ENABLE SPINUP) primitive, the drive
waits for a START STOP UNIT command with the START bit equal to 1. After receiving a START STOP UNIT command with the START bit equal to 1,
the drive waits for a NOTIFY (ENABLE SPINUP) primitive. After receiving a NOTIFY (ENABLE SPINUP) primitive through either port, the drive
becomes ready for normal operations within 30 seconds (excluding the error recovery procedure).
If the drive receives a START STOP UNIT command with the START bit and IMMED bit equal to 1 and does not receive a NOTIFY (ENABLE SPINUP)
primitive within 5 seconds, the drive fails the START STOP UNIT command.
The START STOP UNIT command may be used to command the drive to stop the spindle. Stop time is 23 seconds (maximum) from removal of DC
power. SCSI stop time is 23 seconds. There is no power control switch on the drive.
An unexpected power loss event, spin up at cold or hot temperature extremes may cause the drive to exceed the typical and max time to ready by
5 to 20 seconds. Extended time to ready is dependent on cache state and environmental conditions prior to the unexpected power loss and
during the subsequent power on.
Minimum sector interleave
1 to 1
Maximum Internal data rate*
2.7 Gb/s
Sustained transfer rate
103 to 258 MiB/s **
SAS Interface maximum instantaneous transfer rate
1200MB/s* per port
(dual port = 2400MB/s*)
Logical block sizes
512 (default), 520 or 528.
4096, 4160 or 4224.
Read/write consecutive sectors on a track
Yes
Flaw reallocation performance impact (for flaws reallocated at format time using the spare
sectors per sparing zone reallocation scheme.)
Negligible
Average rotational latency
4.16ms
*Assumes no errors and no relocated logical blocks. Rate measured from the start of the first logical block transfer to or from the host.
** MiB/s x 1.048 = MB/s
