Table 10: Summary of the performance and price-performance of SCSI and IDE drives
|
SCSI: Quantum Atlas
|
IDE: Quantum Fireball
|
GB/drive
|
18
|
26
|
KAPS/drive (KB accesses/s/disk)
|
105
|
78
|
MAPS/drive (MB accesses/s/disk)
|
20
|
15
|
$/drive
|
534
|
209
|
MB/$
|
34
|
124
|
KAPS/$
|
0.20
|
0.37
|
MAPS/$
|
0.04
|
0.07
|
Network access to local and remote files has high overhead and some serious performance problems. The good news is that using Gigabit Ethernet, a client can read at nearly 40MBps from a server and can write at half that rate. But there are many irregularities in the performance curves, and the overheads are quite high.
Table 11. Cpu cost of IOs on 733MHz Pentium III.
|
Random 8KB
|
Buffered
|
Read
|
150 μs
|
Write (= 64KB read + 8KB write)
|
275 μs
|
Unbuffered
|
Read
|
70 μs
|
Write
|
85 μs
|
|
Fixed (us)
|
Marginal (us/KB)
|
Sequential
|
Buffered
|
Read
|
12 μs
|
6 μs /KB
|
Write
|
12 μs
|
7 μs /KB
|
UnBuffered
|
Read
|
50 μs
|
0.5 μs /KB
|
Write
|
50 μs
|
0.5 μs /KB
|
Network sequential (CIFS/SMB)
|
UNC local
|
Read and write
|
450 μs
|
450 μs /KB
|
Mapped local
|
Read and write
|
560 μs
|
560 μs /KB
| Acknowledgements
Thanks go to Maurice Franklin for allowing us to use some of his code as our primary test program. Maurice Franklin and Bruce Worthington also deserve thanks for allowing us to consult them with our questions.
Thanks also to Jim Gemmell and Don Slutz for giving us a better understanding of Windows 2000. Jim Gemmell also helped us better understand disk caching and scheduling algorithms.
References
[Horst] Horst, Robert, “TwinStor Technology: A Compelling Case for Multiple Drives in PCs, Servers, and Workstations,” 3ware Technical Report TR-1999-2, 1999. http://www.3ware.com/products/TwinStor.pdf
[Nagar] Nagar, Rajeev. Windows NT File System Internals: A Developer’s Guide. Sebastopol, CA: O’Reilly & Associates, 1997.
[Rambus] Rambus Based Products Benchmarks. http://www.rambus.com/products/products_benchmark_840.html
[Riedel] Riedel, Erik, Catherine van Ingen, and Jim Gray. “A Performance Study of Sequential IO on WindowsNT 4.0,” Microsoft Research Technical Report MSR-TR-97-34, 1997.
[ZD] Ziff Davis WinBench 99 Benchmark. http://www.zdnet.com/zdbop/stories/main/0,8829,2326114,00.html
[Hennesy&Patterson] Hennessy, John L. and David A. Patterson. Computer Architecture: A Quantitative Approach. Palo Alto, CA: Morgan Kaufmann Publishers Inc., 1990.
[Richter] Richter, Jeffery. Advanced Windows: The developer’s Guide to the Win32 API for Windows NT 3.5 and Windows 95. Redmond, WA: Microsoft Press, 1995.
[Solomon] Solomon, David A. Inside Windows NT Second Edition. Redmond, WA: Microsoft Press, 1998.
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