At 06:02 9/21/2003, you wrote:You may well be right for this class of machine. EIDE drives are 7200rpm and you'll get an average access speed of 9ms (or thereabouts). You'll get a sustained throughput of about 50Mb/s on the disks and whatever the array will support when you can double up on disks. With a SCSI array and 10K rpm disks you'll get an average access time of 6ms, with 15K disks you're down to around 4.5ms (I think those numbers are right. On the other hand, as you rightly point out, you can double the number of I/Os per second, for, oh, only two or three times the price :-) You can claw that difference back by having more EIDE drives (I don't know what the 3Ware controller supports).
Having said all that, for a few hundred users, get a Dell Poweredge 1650 two CPUs with about 1G memory, and a megaraid controller. You'll need a SCSI disk array and about half a dozen disks (mirrored and striped, RAID5 doesn't have the write performance you'll need for mail and file serving.
I would actually disagree here. Given the cost of the "SCSI disk array and about half a dozen disks", I would much rather purchase an off-the-shelf 3Ware 7500-8 or -12 card with EIDE drives or (better yet) SATA drives. Save at least hundreds if not a couple thousand dollars, and get performance practically the same. Also, the more drives in the array, the faster the read speeds.
And again -- if this is a production server you *must* consider support and maintenance. If you can't buy a supported machine with a 3Ware controller, pay the extra and get a SCSI machine which is supported. And don't forget that the Megaraid controller and SCSI disks are well-established technology. There's a lot to be said for conventional technology when you're building a server -- servers really do need to be reliable.
jch
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