Date: Tue, 27 Mar 2001 18:19:00 -0500 From: "Ed Henderson" <Ed.Henderson@Certainty.net> To: "'Michael VanLoon'" <MichaelV@EDIFECS.COM>, "'Andrew C. Hornback'" <hornback@wireco.net>, "'Joseph Gleason'" <clash@fireduck.com> Cc: "'FreeBSD Hardware'" <hardware@FreeBSD.ORG>, "'Mike Smith'" <msmith@FreeBSD.ORG> Subject: RE: Server MB suggestions? Message-ID: <003101c0b714$4ec47260$0464a8c0@pnt004> In-Reply-To: <F37F6A0194D1EF4BA8D0EF3B542BE3E00F155D@ecx1.edifecs.com>
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OK, OK!!! I give in I'm going SCSI (small cheer from the cheap seats!). Here is what I'm going to use: 1. Lets assume for now that I will use a standard 2 channel SCSI controller (non-RAID) and will use software RAID-1 with one 36GB drive on each channel. Any controller recommendations? 2. What drives do you recommend - manufacturer, model. 3. Should I go for 160MB/s or stick with 80MB/s drives? I am trying to be reasonable in cost. 4. I plan to have an external DDS-4 DAT tape drive attached to one of the channels. Any suggestions? Many thanks to all contributors! Ed. > > I think you have that backwards. Reading mirrors, with a > good controller, > increases performance, not decreases. A good hardware RAID > controller will > interleave read requests from mirrored drives so you can > approach double the > read throughput of a single drive. > > And writes should be the same speed (roughly) writing to two > drives as one, > since they're simultaneous. Of course in reality, bus > bandwidth comes into > play, and is one of the reasons lots of installations install > each pair of > mirrored drives on separate SCSI busses. > > Here are the benefits of SCSI hardware RAID over IDE RAID: > > - More performance with lots of drives, both because you can have more > drives on more busses, and because the RAID is actually > happening on the > controller (many IDE "hardware" RAID controllers do only the > basic work > needed, and much is still done in the BIOS or the OS). > > - More extensible. With a 3-bus SCSI controller you can hang up to 45 > devices off it. It's pretty easy to max out an IDE RAID > controller and have > nowhere to go. > > - More easily extensible. A good hardware RAID controller > will allow you to > do dynamic expansion of the volume. I.e., throw a couple > more drives on, > tell the controller to expand it, it does so in the > background, rearranging > the pieces of the array for optimum performance, and viola, you have a > larger virtual drive. Then you just need to use the OS to > either expand the > filesystem/partition (i.e. growfs), or add a new one. > > - Reliability. SCSI drives are simply more reliable. IDE > drives are made > with cost as the primary requirement. They fail more often. > Please don't > flame me on this. Yes, SCSI drives fail, and yes lots of IDE > drives last a > long time, but over a large sample, it's pretty much a fact > that IDE drives > have more failures than SCSI drives. > > On the other hand, yes modern IDE drives are fairly well > built, pretty fast, > and cheap cheap cheap. Balance as your needs, comfort level > and budget can > accommodate. > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hardware" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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