Date: Fri, 30 May 1997 09:29:29 +0200 From: j@uriah.heep.sax.de (J Wunsch) To: chat@FreeBSD.ORG (FreeBSd Chat list) Cc: francisco@natserv.com (Francisco Reyes) Subject: Re: IDE or Ultra SCSI Message-ID: <19970530092929.CP11088@uriah.heep.sax.de> In-Reply-To: <199705300343.XAA01738@federation.addy.com>; from Francisco Reyes on May 29, 1997 23:17:59 -0400 References: <199705300343.XAA01738@federation.addy.com>
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As Francisco Reyes wrote: > I have been agonizing for a few days trying to decide whether to get > IDE or Ultra SCSI. For me, the question would be quite simple to answer. :-) But i don't have an IDE drive at all, but two SCSI buses in each of my machines at work and home. :) IDE is in theory as fast as SCSI. However, we don't support busmaster DMA for IDE yet, and thus you eat up valuable CPU cycles with an IDE drive, that could be spent better in serving processes on a multiprocessing system. Also, i basically love the flexibility with SCSI. Two devices vs. seven devices per bus makes a difference for me. I am currently using or have been using the following classes of devices: fixed disk, optical disk, CD-ROM, CD-ROM changer, CD-R, scanner, various tape drives. IDE will have to go a very long way still until they can provide this variety (and even longer until they'll have it hot- pluggable ;-). SCSI is a standard, while the ATA specs is something that dares to call itself a standard, but is in fact a pile of crap not worth the 100+ pages of paper you use to print it on. Have a look there if you don't believe me. I'm always impressed again that it works a little bit at all, hats off to Søren for the basically working ATAPI CD-ROM driver. After reading this so-called standard, the only impression you get is that all this _cannot_ work. At least, not reliably. (You get this at least, if you've read SCSI before.) ``Ultra'' is more of a marketing gag than real value, it just means ``use double the clock rate, and allow for only half the cable length''. Fortunately, you can turn it off. With only one ore two disks, you don't need the peak transfer rate anyway, and the slow peripherals don't account much to the bus saturation. > The difference in price betwen IDE and Ultra is about $700. Is it worth > it? Why is it so much? You don't necessarily need the expensive Adaptecs. I'm using two AHA-2940 at work, but two NCR 53c810 at home. Both systems work fine, and i don't see a burning need to spend so much more money into the Adaptecs. (I also used to run mixed NCR/Adaptec at home, and have only bought a second NCR since i needed to free up the Adaptec i've borrowed from my employer. The mix system worked well, too.) -- 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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