Author: David Rasmussen
Date: 13:48:18 01/16/03
Go up one level in this thread
On January 16, 2003 at 16:36:26, Robert Hyatt wrote: > >Sorry, but maybe you are right, "they are not as bad as I think." > >They are _worse_. > >:) > >Believe me, compared to good SCSI drives, anything IDE simply crawls. I have >some of the fastest IDE drives around on machines here and they don't even get >into the same ballpark with U320 15K scsi drives. IE average latency=2ms. 320 >megabytes/sec burst transfer. Very difficult to even imagine an IDE drive that >fast. > The real life transfer rate of SCSI disks that I've used is not that much greater than for good IDE disks. Interface rates are another matter. The differences can be important in many settings, mostly multi user environments with many different I/O requests. But on a single user machine running dedicatedly a chess program, I don't think the difference is huge. Again, I might be wrong. > >> >>I know it's slower, but very few people are not using disks comparable to mine, >>and they don't seem to have a problem. Disks such as yours are not strictly >>necesary, I would think. Maybe I'm wrong. Also, I still think you are >>underestimating the performance of current IDE drives. I don't believe that >>fraction is very small. > >We are talking a factor of 2-3-4 at _least_. And when you get an IDE drive >going >fast, it saturates the bus and stops everything else. What? > SCSI doesn't. Try >working on a >machine with IDE vs a machine with SCSI and fire up a huge I/O copy. You can't >notice with SCSI. With IDE you can't use the machine. > You're working with either an old disk or an old controller/motherboard. Modern IDE incarnations use bus mastering and DMA etc. that makes those statemenst untrue. And the SCSI harddisks I work with are not unnoticable. I can easily feel when they work. There is a SunBlade machine I work with, and it has a 10.000RPM SCSI something disk, and the machine is not unaffected when the disk works. It actually feels slower to work with than a good modern PC with a good IDE drive. >> >>>You might try upping the egtb cache size significantly to avoid some I/O. >>> >> >>To how much, would you say? I tried going from 8MB to 64MB just now, and it >>didn't help at all. In fact, it was slower. >> >>/David > >If it is slower you have something else wrong. IE you must be paging. Back off >the size >of the normal hash stuff as making the egtb cache bigger should not slow you >down _ever_. >unless it begins to cause paging. OK, I'll test... /David
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