Ziff Davis Winbench 98 |
|||
Business Disk WinMark 98 (KB/s) |
1254 |
1110 | |
SS/Database |
1128 |
987 | |
WP |
1522 |
1338 | |
Publishing |
1144 |
1046 | |
Browsers |
1426 |
1234 | |
Task Switching |
1822 |
1618 | |
High-End Disk WinMark 98 (KB/s) |
3722 |
3226 | |
AVS/Express 3.1 |
2306 |
2008 | |
Frontpage 97 |
2920 |
2818 | |
MicroStation 95 |
7032 |
6090 | |
Photoshop 4.0 |
3038 |
2488 | |
Premiere 4.2 |
6952 |
5918 | |
PV-Wave 6.1 |
2720 |
2264 | |
Visual C++ 5.0 |
8220 |
7160 | |
Disk/Read Random Access (ms) |
16.3 |
18.0 | |
Disk/Read Transfer Rate (KB/s) |
|||
Beginning |
11800 |
11200 | |
End |
7170 |
6800 | |
Disk/Read CPU Utilization (%) |
5.9 |
3.9 | |
Transfer Rate (KB/s) |
11758 |
7388 |
CPU utilization per megabyte transferred for both drives are virtually identical. There's a common perception floating around that ATA's CPU utilization even with busmaster drivers does not approach that of busmastering SCSI. CPU utilization scores of ATA drives when using the busmaster drivers including with Windows 95 OEM Service Release 2 indicate otherwise, however. SCSI does not have an advantage here.
ATA drives and controllers, on the other hand, do not offer a key SCSI feature: Command Queuing. This feature allows multiple requests to "queue" and remain pending on the SCSI subsystem as opposed to ATA's serial approach where one request must be finished before another is started. This parallel execution allows SCSI to reorder the requests into a sequence that minimizes head/actuator seek motions. Simply put, SCSI's advanced features should result in less degradation in multitasking and multithreaded environments.
We decided to turn to Adaptec's ThreadMark 2.0 Benchmark. Adaptec offers the benchmark as a more reliable indicator of overall disk performance in multitasking environments. ThreadMark is difficult to run consistently, however. To obtain repeatable results, the test machine's use of virtual memory must be disabled. Storage Review's testbed has 64 megs of RAM, enough to run most applications well, but -not- enough to guarantee stability without any virtual memory. With virtual memory enabled, ThreadMark results varied wildly, sometimes displaying sample deviations of over 100%. Disabling virtual memory contained the sample deviations to a much more usable 1%. The average of five trials is presented here.
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