IBM DDRS-39130 - Ultrastar 9.1 GB Hard Drive

3.4.7 Throughput
3.4.7.1 Simple Sequential Access
The above table gives the time required to read/write for a total of 8000x consecutive blocks (16,777,216
bytes) accessed by 128 read/write commands. Typical and Max values are given by 105% and 110% of T
respectively throughput following performance description.
Note: Assumes a host system responds instantaneously.
T = (A * 128) + B + C + 16,777,216/D + 512/E (READ)
T = (A * 128) + B + C + 16,777,216/D (WRITE)
where:
T = Calculated Time (sec)
A = Command Process Time (Pre/Post Command overhead)
B = Average Seek Time
C = Average Latency
D = Sustained Disk-Buffer Transfer Rate (Mbyte/sec)
E = Buffer-Host Transfer Rate (Mbyte/sec)
3.4.7.2 Random Access
The above table gives the time required to execute a total of 1000x read/write commands which access a
random LBA.
T = (A + B + C + 512/D + 512/E) * 4096 (READ)
T = (A + B + C + 512/D) * 4096 (WRITE)
where:
T = Calculated Time (sec)
A = Command Process Time (Pre/Post Command overhead)
B = Average Seek Time
C = Average Latency
D = Sustained Disk-Buffer Transfer Rate (Mbyte/sec)
E = Buffer-Host Transfer Rate (Mbyte/sec)
Figure 12. Simple Sequential Access Performance
Operation Typical Max
Sequential Read/Write Zone 0 1300 [msec]
Zone 7 1348 [msec]
Zone 0 2086 [msec]
Zone 7 2172 [msec]
Figure 13. Random Access Performance
Operation Typical Max
Random Read 52.2 [sec] 54.7 [sec]
Random Write 55.2 [sec] 57.8 [sec]
Drive Characteristics 15