Date: Mon, 12 Apr 1999 22:22:34 -0600 (MDT) From: "Kenneth D. Merry" <ken@plutotech.com> To: remy@synx.com Cc: freebsd-scsi@FreeBSD.ORG Subject: Re: Huge SCSI configs Message-ID: <199904130422.WAA09582@panzer.plutotech.com> In-Reply-To: <199904121804.UAA30722@rt2.synx.com> from Remy Nonnenmacher at "Apr 12, 1999 8: 4:31 pm"
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Remy Nonnenmacher wrote... > I am looking for advices about building a fearly huge SCSI config. > > The config would be : > > - 4 SCSI chains (2x3950U2W planned) That should work okay, as long as you use -current or -stable *after* March 23rd. I've got one in my test box, and it seems to work fine. I haven't pushed it much, though. One thing to be careful about is what sort of slot you put this thing in. If you get a motherboard with only 32-bit slots, you need to make sure that the back end of the PCI slots is thin enough to handle a 64-bit PCI card. There was one machine that I tried to put my 3950 into that it wouldn't fit in, because the back end of the slot was too thick. It worked fine in two other machines, though. > - 12 18.2 GB per chain (48 totals disks) Well, first off, make sure you get IBM or Seagate, and make sure you get one of their high end drives. (not that they're making low-end 18 gig drives yet, AFAIK) I've had direct experience with the 18G Seagate Cheetah II's and IBM Ultrastar 18XP's. They both work fine. My guess is that the IBM Ultrastar 18ZX would work well, too. You should be okay with most any 18G IBM or Seagate disk. But 12 per chain? Assuming these are all Ultra2 LVD, you're still pushing things a bit as far as SCSI bus bandwidth is concerned. For instance, the IBM Ultrastar 18ZX runs at about 23MB/sec on the outer tracks according to IBM's web site. With that sort of performance, you wouldn't be able to get maximum performance out of the disks if had more than 3 on an Ultra 2 chain. You'll also have to start worrying about PCI bus bandwidth and memory bandwidth, depending on what sort of motherboard you get. So, one question I have is this -- are you looking for maximum disk performance, or just a lot of disk space? If you're just looking for a lot of disk space, why not go with 36GB drives? NECX (www.necx.com) is selling IBM Ultrastar 36XP's for $1400. The Ultrastar 18ES is selling for $775. So, it would be cheaper to go with a 36G drive. (FWIW, I know that the 36XP's work just fine, but I haven't seen any 18ES drives yet. I'd imagine they work fine as well.) > - one Gigabit ethernet link Isn't there only one gigabit ethernet driver (Alteon?) at the moment? You should probably ask Bill Paul how it works. You may also want to ask David Greenman about this, since I think he mentioned on -current a while back that he was working on a Gigabit Ethernet driver as well. > - SMP (Quad-Xeon or Bi-P2) Considering the monster you're trying to build, I'd say go for a board that'll get you 64-bit PCI and high memory bandwidth. My guess is that a Quad Xeon board from Intel might do the trick. Ask Mike Smith about these, they had (have??) one at Walnut Creek, I think. From looking at Intel's web page, it looks like you should probably be looking at the AC450NX and the AD450NX servers. You may want to find someone who has one of these, or has tried one out before buying. > Advices wanted (do/don't). I would advise that you thoroughly research things before you buy any hardware. The hardware you're looking at is cutting edge, but there are folks who have "been there, done that" with each item you listed above. If you buy the wrong thing, you can potentially waste a whole lot of money. Ken -- Kenneth Merry ken@plutotech.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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