From owner-freebsd-hackers Fri Mar 3 18:45:41 2000 Delivered-To: freebsd-hackers@freebsd.org Received: from mta4.rcsntx.swbell.net (mta4.rcsntx.swbell.net [151.164.30.28]) by hub.freebsd.org (Postfix) with ESMTP id E52F837B74C for ; Fri, 3 Mar 2000 18:45:37 -0800 (PST) (envelope-from jbryant@ppp-207-193-2-159.kscymo.swbell.net) Received: from ppp-207-193-2-159.kscymo.swbell.net ([207.193.2.159]) by mta4.rcsntx.swbell.net (Sun Internet Mail Server sims.3.5.1999.09.16.21.57.p8) with ESMTP id <0FQV0092GMBSCC@mta4.rcsntx.swbell.net> for freebsd-hackers@FreeBSD.ORG; Fri, 3 Mar 2000 20:45:31 -0600 (CST) Received: (from jbryant@localhost) by ppp-207-193-2-159.kscymo.swbell.net (8.9.3/8.8.5) id UAA10031; Fri, 03 Mar 2000 20:45:25 -0600 (CST) Date: Fri, 03 Mar 2000 20:45:18 -0600 (CST) From: Jim Bryant Subject: Re: Copy-on-write filesystem In-reply-to: To: mbac@nyct.net (Michael Bacarella) Cc: freebsd-hackers@FreeBSD.ORG Reply-To: kc5vdj@swbell.net Message-id: <200003040245.UAA10031@ppp-207-193-2-159.kscymo.swbell.net> MIME-version: 1.0 X-Mailer: ELM [version 2.4ME+ PL32 (25)] Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7bit X-Windows: R00LZ!@# MS-Winbl0wz DR00LZ!@# X-files: The truth is that the X-Files is fiction X-Republican: The best kind!!! X-Operating-System: FreeBSD 4.0-CURRENT #8: Sat Oct 30 00:56:56 CDT 1999 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG 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