Date: Fri, 26 Jun 1998 07:00:25 -0700 From: David Greenman <dg@root.com> To: Thomas David Rivers <rivers@dignus.com> Cc: hackers@FreeBSD.ORG Subject: Re: Heads up: block devices to disappear! Message-ID: <199806261400.HAA10810@implode.root.com> In-Reply-To: Your message of "Wed, 24 Jun 1998 10:01:52 EDT." <199806241401.KAA04665@lakes.dignus.com>
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>Terry Lambert writes: >> had in no other fashion. Let's meake sure that the block device interface >> is not in the same [complex but useful - ed.] category before summarily >> executing it. > > In a similar context - I'd like to ask some simple questions. > > Can anyone clearly state why they were needed in UNIX at it's offset? > > Once that is understood - is it still the case, or has it been obviated > in some way? > > I believe answers to these questions would be illuminating for the > nervous amongst us (I count myself in the 'nervous' category on this one.) > > The reason I call for caution is simple - these have been with UNIX > a long time... if they could have been simplified at the offset, why > weren't they? What's different now? > > I'm not saying it's a bad idea, I'd just like to understand what's > changed from 20+ years ago... All caching in Unix used to be device-based and the block device was the thing being cached (as opposed to the character device which is uncached). Starting with 4.4BSD, the cache is file-based, making the main reason for the existence of the block device obsolete. -DG David Greenman Co-founder/Principal Architect, The FreeBSD Project To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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