Performance Characteristics; Command Overhead; Figure 6. Performance Characteristics - IBM DJSA-210 - Travelstar 10 GB Hard Drive Specifications

4.5 Performance characteristics

File performance is characterized by the following parameters:

! Command Overhead

! Mechanical Positioning
! Seek Time
! Latency
! Data Transfer Speed
! Buffering Operation (Look ahead/Write Cache)
Note: All the above parameters contribute to file performance. There are other parameters which contri-
bute to the performance of the actual system. This specification defines the essential file characteristics.
This specification does not include the system throughput as this is dependent upon the system and the
application.
The following table gives a typical value for each parameter. The detail descriptions are found in
section 5.0.
Average Random Seek Time For Read (ms)
Average Random Seek Time For Write (ms)
Rotational Speed (RPM)
Power-on-to-ready (sec)
Command overhead (ms)
Disk-buffer data transfer (Mb/s)
Buffer-host data transfer (MB/s) (PIO Mode-4)

Figure 6. Performance characteristics

4.5.1 Command overhead
Command overhead time is defined as the interval from the time that a drive receives a command to the
time that the actuator starts its motion.
Function
(Ultra DMA Mode-4)
Travelstar 33GH/30GT/20GN hard disk drive specifications
Typical Typical
DJSA-232 DJSA-230
12
13
5400 4200
5.0
1.0
120-223 109-203
16.6
66.6
13
Typical
DJSA-220/210/205
12 12
13 13
4200
3.3 3.0
1.0 1.0
109–203
16.6 16.6
66.6 66.6