Date: Fri, 10 Dec 1999 04:32:35 -0700 From: Brett Glass <brett@lariat.org> To: Terry Lambert <tlambert@primenet.com>, des@flood.ping.uio.no (Dag-Erling Smorgrav) Cc: andrews@technologist.com, Doug@gorean.org, bright@wintelcom.net, chat@FreeBSD.ORG, doconnor@gsoft.com.au, dscheidt@enteract.com Subject: Re: dual 400 -> dual 600 worth it? Message-ID: <4.2.0.58.19991210042304.048a2c90@localhost> In-Reply-To: <199912100213.TAA04264@usr02.primenet.com> References: <xzpzovla51w.fsf@flood.ping.uio.no>
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At 07:13 PM 12/9/1999 , Terry Lambert wrote: >It's constantly amazing to me that the same people who state >that FreeBSD should not go after the desktop and should not >have graphical logins and other destop workstation fluff, are >the same people who claim that IDE is as good as, or better >than, SCSI. > >Perhaps for a single user workstation, IDE _is_ better than >SCSI. All of the benchmarks that claim this are non-concurrent, >after all, just like the one application likely to be running >at a time on a single user workstation. > >For heavily loaded servers, howwever, there is absolutely no >comparison: SCSI wins because of concurrency, and latency for >single-user, single-threaded operations be damned. I think the real question is, "Can the host CPU provide that concurrency as effectively as the embedded CPU in the drive?" If it can at least get close, one probably won't see a significant difference in performance; the host CPU will do the same scheduling that the embedded processor would, and the raw hardware (the disk and heads) will be used about as efficiently. I honestly don't know how clever the controllers in Joe SCSI Drive are, or how boneheaded (or smart!) a UNIX file system can be as regards efficient use of the disk, so I'll admit that I don't know if this is the way it works on a FreeBSD system. I do suspect that in a RAID system, it might actually be *better* to have IDE drives in the array and a SCSI interface to the computer, since the RAID controller is expected to take concurrency and head position into account. And the "I" in RAID does stand for "inexpensive," which means that, these days, it might as well stand for "IDE." --Brett To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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