Date: Fri, 03 Mar 2000 20:45:18 -0600 (CST) From: Jim Bryant <jbryant@ppp-207-193-2-159.kscymo.swbell.net> To: mbac@nyct.net (Michael Bacarella) Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Copy-on-write filesystem Message-ID: <200003040245.UAA10031@ppp-207-193-2-159.kscymo.swbell.net> In-Reply-To: <Pine.BSF.4.05.10003031338080.1135-100000@bsd1.nyct.net>
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In reply: > Imagine: cp file file2, file and file2 reference the same exact blocks, > but modified chunks of file2 would be given their own private blocks. This is not a microsoft innovation, actually, I believe it was a VMS innovation. It's called a generational filesystem. the original is stored, and later generations of the file are stored as diffs. > This probably won't fit into current filesystems, but is it a sane idea > worth pursuing in a new filesystem? I performed an analysis on a > non-production server and determined that about 66 megs of a typical > FreeBSD install is duplicate files (and yes, I ignored hard links and > symlinks and non-regular files). it has it's advantages. and disavantages. one problem in VMS is determining the system-wide policy on such things, such as how many file generations will be kept. this isn't exactly apples to apples, but it's close enough to be discussed. a VMS style filesystem would be interesting. jim -- All opinions expressed are mine, if you | "I will not be pushed, stamped, think otherwise, then go jump into turbid | briefed, debriefed, indexed, or radioactive waters and yell WAHOO !!! | numbered!" - #1, "The Prisoner" ------------------------------------------------------------------------------ KC5VDJ - HF to 23cm KC5VDJ@NW0I.#NEKS.KS.USA.NOAM kc5vdj@swbell.net IC-706MkII, IC-T81A, HTX-202, HTX-212, HTX-404, KPC3+, PK-232MBX Grid: EM28px ------------------------------------------------------------------------------ ET has one helluva sense of humor, always anal-probing right-wing schizos! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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