Performance with multiple drives
Hello list,
I am experiencing a performance hit on my SCSI setup here and am wondering if this is to be expected or whether there is anything I can do about it. In summary, when reading from a single drive, I am getting read performance of approx 73mb/s, when reading from two drives concurrently, regardless of which two, reads drop to 64mb/sec per drive and when reading from all three, read performance is approximately 46mb/sec. The drives are matched Maxtor Atlas 10K IV sca units using a dual channel u160 onboard aic7xxx controler. Two drives are on channel 0 and the third is on channel 1. The drives are sca units so I had to use 80/68 pin converters on all three in case that would make a difference as I couldn't find a scsi backplane which would support splitting the drives across the channels as is necessary due to the 160mb/sec channel limit.
The system is a dual Pentium III tualatin setup with 1gb of ram. The board claims to support 64 bit 66mhz pci on the scsi bus and I have no legacy cards on that particular bus so it should be running at 64 bit. However, I don't know of a way to verify that under linux.
If anyone has any suggestions on how I can find the bottleneck, I would appreciate it.
Best,
Shane
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Shane Wegner http://www.cm.nu/~shane/