Seagate ST336918N, ST318418N manual Ultra2 SCSI, Ultra160 SCSI, Notes for Section, Start/stop time

Barracuda 36ES2 Product Manual, Rev. B		9
SCSI interface data transfer rate (asynchronous):
Maximum instantaneous one byte wide	5.0 Mbytes/sec [4]
Maximum instantaneous two bytes wide	10.0 Mbytes/sec [4]
Synchronous formatted transfer rate	Ultra2 SCSI	Ultra160 SCSI
In single-ended (SE) interface mode	5.0 to 40 Mbytes/sec	5.0 to 80 Mbytes/sec
In low voltage differential (LVD) interface mode	5.0 to 80 Mbytes/sec	5.0 to 160 Mbytes/sec

Sector Sizes:
Default	512 byte user data blocks
Variable	512 to 4,096 bytes per sector in even number of bytes per sector.
	If n (number of bytes per sector) is odd, then n-1 will be used.

Read/write consecutive sectors on a track	Yes
Flaw reallocation performance impact (for flaws reallocated at format time using	Negligible
the spare sectors per sparing zone reallocation scheme.)
Average rotational latency	4.17 msec

Notes for Section 4.2.

[1]Execution time measured from receipt of the last byte of the Command Descriptor Block (CDB) to the request for a Status Byte Transfer to the Initiator (excluding connect/disconnect).

[2]Typical access times are measured under nominal conditions of temperature, voltage, and horizontal ori- entation as measured on a representative sample of drives.

[3]Assumes no errors and no sector has been relocated.

[4]Assumes system ability to support the rates listed and no cable loss.

[5]Access time = controller overhead + average seek time.

Access to data = controller overhead + average seek time + latency time.

4.3Start/stop time

After DC power at nominal voltage has been applied, the drive becomes ready within 20 seconds if the Motor Start Option is disabled (i.e. the motor starts as soon as the power has been applied). If a recoverable error condition is detected during the start sequence, the drive executes a recovery procedure which may cause the time to become ready to exceed 20 seconds. During spin up to ready time the drive responds to some com- mands over the SCSI interface in less than 3 seconds after application of power. Stop time is less than 15 sec- onds from removal of DC power.

If the Motor Start Option is enabled, the internal controller accepts the commands listed in the SCSI Interface Product Manual less than 3 seconds after DC power has been applied. After the Motor Start Command has been received the drive becomes ready for normal operations within 10 seconds typically (excluding an error recovery procedure). The Motor Start Command can also be used to command the drive to stop the spindle (see SCSI Interface Product Manual, part number 75789509).

There is no power control switch on the drive.

4.4Prefetch/multi-segmented cache control

The drive provides prefetch (read look-ahead) and multi-segmented cache control algorithms that in many cases can enhance system performance. “Cache” as used herein refers to the drive buffer storage space when it is used in cache operations. To select prefetch and cache features the host sends the Mode Select command with the proper values in the applicable bytes in Mode Page 08h (see SCSI Interface Product Manual, part number 75789509). Prefetch and cache operation are independent features from the standpoint that each is enabled and disabled independently via the Mode Select command. However, in actual operation the prefetch feature overlaps cache operation somewhat as is noted in Section 4.5.1 and 4.5.2.

All default cache and prefetch Mode parameter values (Mode Page 08h) for standard OEM versions of this drive family are given in Tables 8 and 9.