Table of Contents
Advertisement
10
SCSI interface data transfer rate (asynchronous) [4]:
Maximum instantaneous (16 bit wide)
Maximum instantaneous (8 bit wide)
Synchronous transfer rate for SCSI Fast-20 (Ultra SCSI):
8 bit data bus (N model)
16 bit data bus (W/WC/WD/DC models)
Sector Sizes
Default
512-byte user data blocks
Variable
180 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
Flaw reallocation performance impact:
For flaws reallocated at format time
For flaws reallocated using the spare sectors per cylinder reallocation scheme
Overhead time for head switch (512-byte sectors) in sequential mode
Overhead time for one track region switch in sequential mode
Average rotational latency
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]
Rate measured from the start of the first sector transfer to or from the host.
[5]
Assumes system ability to support the rates listed and no cable loss.
[6]
Access time = controller overhead + average seek time
Access to data = controller overhead + average seek time + latency time
4.3
Start/stop time
After DC power at nominal voltage has been applied, the drive becomes ready within 30 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 30 seconds. During spin up to ready time the drive responds to some com-
mands over the SCSI interface. Stop time is less than 30 seconds 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 30 seconds typically (excluding an error
recovery procedure). The Motor Start command can also be used to command the drive to stop the spindle
(see the SCSI Interface Product Manual , P/N 77738479).
There is no power control switch on the drive.
4.4
Prefetch/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 com-
mand with the proper values in the applicable bytes in Mode Page 08h (see the SCSI Interface Product Man-
Cheetah 4LP Product Manual, Rev. B
10.0 Mbytes/sec [5]
5.0 Mbytes/sec [5]
2.5 to 20 Mbytes/sec
5.0 to 40 Mbytes/sec
Yes
Negligible
5.98 msec (minimum)
17.94 msec (maximum)
0.798 msec
1.064 msec (typical)
2.99 msec
Advertisement
Table of Contents
