Date: Sat, 31 May 1997 10:51:19 +0200 From: j@uriah.heep.sax.de (J Wunsch) To: freebsd-chat@FreeBSD.ORG Subject: Re: IDE or Ultra SCSI Message-ID: <19970531105119.HZ10573@uriah.heep.sax.de> In-Reply-To: <199705301207.WAA15894@ogre.dtir.qld.gov.au>; from Stephen McKay on May 30, 1997 22:07:35 %2B1000 References: <199705300343.XAA01738@federation.addy.com> <19970530092929.CP11088@uriah.heep.sax.de> <199705301207.WAA15894@ogre.dtir.qld.gov.au>
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As Stephen McKay wrote: > >IDE is in theory as fast as SCSI. > Is IDE (in theory) really as good? I understood that only one outstanding > command was possible with IDE, meaning only one disk could be active at > a time, versus many simultaneous commands with SCSI. Am I out of date? I rather meant the plain transfer rates. The fastest IDE modi aren't slow, and on the PCI bus, even PIO isn't such a slow dog as it used to be with ISA, where every IO cycle has been inflated to 1.25 µs. Of course, you're right regarding bus disconnection (and you would be even more right regarding tagged command queuing, but you didn't mention it :). > On the other hand, Ultra Wide is where it's all going. Or so it > looks to me. But nobody tells you you _must_ turn on this 20 MHz stuff. You can still run it at 10, and totally ignore the Marketing-Ultra. Wide can give you better throughput if you need it (without the cable length limitation problems). Curious, are there 32-bit wide devices available now? > For example, I could go to a nearby computer shop and buy a 6Gb IDE disk > for AU$600, or a 4Gb SCSI3 disk for AU$1100. I've recently read a marketing fax, announcing Seagate products... They really build a 23 GB drive these days. *shudder* (I think it has been announced for < DEM 5000, reseller price, excluding tax. 1 USD ~ 1.7 DEM these days.) -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)
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