Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site yetti.UUCP Path: utzoo!mnetor!yetti!eriks From: eriks@yetti.UUCP (Eriks Rugelis) Newsgroups: net.unix-wizards Subject: Re: RAM disk vs paging + buffer cache Message-ID: <398@yetti.UUCP> Date: Wed, 13-Aug-86 17:26:22 EDT Article-I.D.: yetti.398 Posted: Wed Aug 13 17:26:22 1986 Date-Received: Wed, 13-Aug-86 19:01:20 EDT References: <514@opus.nbires.UUCP> <2979@brl-smoke.ARPA> Reply-To: eriks@yetti.UUCP (Eriks Rugelis) Organization: York University Computer Science Lines: 47 Keywords: dollars and sense In article <2979@brl-smoke.ARPA> gwyn@brl.arpa (Doug Gwyn (VLD/VMB) ) writes: >In article <514@opus.nbires.UUCP> rcd@nbires.UUCP (Dick Dunn) writes: >>What generally-useful features does a RAM disk have that I didn't >>consider? > >The way I look at it, a RAM disk is just one way to exploit cheap >semiconductor technology within the existing model of computation. >RAMs for such use will normally be slower than main memory RAM, >therefore more affordable (min $/bit). Multi-level storage is the >rule with large systems; ideally it would be transparent (as in >Multics), but in practice "permanent storage" (disk) is different >from "temporary storage" (core). > >The RAM disk on my Apple //e is useful because the Apple main >memory management is a botch.. i recently went to a conference/tradeshow with exactly this premise in mind and came away with a different view of the world... the key here is 'affordability'... it is in some ways an unfortunate reality that there is no market and no real supply of 'old technology' semi-conductor memory parts... just about as soon as they are able, semi-conductor manufacturers ramp up production of the latest and greatest generation of memory devices... hence they don't tend to produce lower density parts for very much longer the bottom line is that semi-conductor disks tend to cost MORE per mega-byte because they are made from the same parts as regular memory boards but must also include a whole bunch of extra logic to support some sort of standard disk interface personality the comments that i heard mostly pointed in the direction of loading up one's cpu with memory and working towards enhancing one's ability to cache data in main storage and thus reduce the need to go to disk you can afford to use a RAM disk on your apple because you don't really need all that much of it... in my case, i don't think that anything less than 70 to 100 mega-bytes would suit my ideal case solution (i run about 10 vms vaxen and some sun's) since vms pages from the file system i would need to put a fair chunk it in my ideal semi-disk configuration does anybody out there have some real experience to comment on? i for one would be glad to hear about it -- Voice: Eriks Rugelis Ma Bell: 416/736-5257 x.2688 Electronic: {allegra|decvax|ihnp4|linus}!utzoo!yetti!eriks.UUCP or eriks@yulibra.BITNET