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Newsgroups: comp.os.386bsd.misc Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!agate!library.ucla.edu!csulb.edu!nic-nac.CSU.net!usc!sdd.hp.com!col.hp.com!csn!yuma!lamar.ColoState.EDU!sandylam From: sandylam@lamar.ColoState.EDU (Sandy Lam) Subject: Re: SCASI or IDE disk? Sender: news@yuma.ACNS.ColoState.EDU (News Account) Message-ID: <CunpM0.1J62@yuma.ACNS.ColoState.EDU> Date: Wed, 17 Aug 1994 02:01:12 GMT References: <salem.136.2E48D0EF@hauk.hsr.no> <CuJL5C.z7M@yuma.acns.colostate.edu> <CuLo9s.4pA@tfs.com> Nntp-Posting-Host: lamar.acns.colostate.edu Organization: Colorado State University, Fort Collins, CO 80523 X-Newsreader: TIN [version 1.2 PL2] Lines: 115 ok, first, let me clarify a few things. The PCI0-IDE chip is on a controller card right now. it's totally compatible with old IDE stuff. It does DMA busmatering AND PIO modes this enables it to be used by old BIOSes as if it were an old IDE controller. Right now we have a device driver to load after the boot up sequence to replace the INT 13h call and enable real performance. It's going to be on motherboards so this will already be IN BIOS on the boards tehy get put on. coretest says 15 megs / sec. if we run it in PIO mode, we can get a little under 10 megs / sec. These are also PIO mode 3 and DMA mode 2 drives. : of course you could be caching but we'll assume you know better than to : raise that one.... (I've seen drives with 120r/sec but that's only 6MB/sec) : (and that doesn't count stepping time) we're not caching at the system level. the chip has 4 words of cache inside it, and the newest drives cache a whole track or more internally. : 2/ how do I put this card into a system and (without a special driver or BIOS : prom) get it to be useful. Obviously I need a driver for this board. Standard : IDE (ATA ok?) used programmed I/O so a bus-mastering interface would have just plug it in. this is assuming you've a PCI motherboard :) so the DMA and PIO interfaces have to be so different? not really. if you look at the ATA-2 spec the only difference is some setup, and when yuou transfer data. in PIO (programmed IO) you have to tell the chip to move every bit of data. in DMA you issue a different command and wait for it to be done. From a hardware standpoint it IS radically different. But in software, conformity rules. : > : > also btw, Western Digitals suck rocks at high end performance. : > best i can get out of those puppies is 7 megs/sec. same setup exactly, western digitals always get worse performace. Conners and seagates are the best btw. : explain please.. : If this is sustained throughput, please let us in on the secret as i said, the rates i'm getting is for a program called Coretest which measures disk speed. real rates are a lot lower becasue of DOS overhead. haven't done teh Unix driver yet, so i can't : > : > the downside? i'm developing for these chips, and they're not out : > yet. but soon they'll be integrated on MANY major brand name : > motherboards. : ah yes the "special interface" : We'll write special drivers to use them under Free/Net-BSD as soon as : they appear, and the specs become 'public' (they are going to do that right?) : but don't expect them to be wildly popular or even 'widely available' : the standard IDE interface will rule the IDE drive world for a while. there IS no special interface. it's totally ATA-2. that's our bible. as for adapting *BSD to use them, i'll just add the new stuff into the current IDE stuff. If you look at ATA-2 it has DMA defined, but i'm sure Nct/FreeBSD don't use it. : I think we can consider this a 'specialty product' along with SCSI, : and given the choice, I'd go for SCSI.. as I said, I have : SCSI devices already and I can borrow SCSI devices from the suns : at work etc. I think it sounds great, but ... the chip itself will cost less than $10 and be integrated on many motherboards. : I guess the secret's in the BIOS drivers that will be able to use them, : If we can right drivers for these boards (hey you must be volunteering right?) you assume the interface is ALL different for this don't you? well, makign them work at top speed w/ N/F BSD will be rather easy. : then they will be a useful addition to out system. : The will suffer none of the present IDE draw-backs (CPU hogging etc.). : But they hardly enter into the discussion of "what drive should I buy" : (SCSI or (standard)IDE).. : > : > not that this really helps solve that one dude's problem, : > but i just had to stick up for IDE. lots of ppl have been : > dogging it hard core saying it sucks performancewise and can't : > possibly ever be decent. btw, there are IDE CD ROMs and soon : > IDE ethernet controllers. : Hey there's nothing wrong with the IDE protocol as transmitted across the : ribbon cable.. it's the way it's "usually" controlled.. : i.e. by the CPU directly, that's the problem. and if you are going to buy : a more expensive IDE controller, then why not get a SCSI controller : that's a whole lot more flexible and useful.. : > : > SCSI's got a lot of hype going for it, but don't think IDE is : > going away any time soon. : no, but then remmeber that most IDE implimentation will continue : to eat CPU cycles as well. And I've never seen an IDE tape jukebox.. : > : julian : p.s. I REALLY am interested in hearing more about what EXACTLY your figures : represent.. (remember no caching, just track buffering on the drive allowed) :-) the way i understand coretest, it transmits as much data as it can from the drive for 4 seconds. then it's simple division. The numbers aren't exactly idyllic, but hell, old IDE drives get maybe 2.5 megs/sec by this test. : +----------------------------------+ ______ _ __ : | __--_|\ Julian Elischer | \ U \/ / On assignment : | / \ julian@tfs.com +------>x USA \ in a very strange : | ( OZ ) 300 lakeside Dr. oakland CA. \___ ___ | country ! : +- X_.---._/ USA+(510) 645-3137(wk) \_/ \\ : v