Date: Fri, 3 Mar 2000 13:39:18 -0500 (EST) From: Michael Bacarella <mbac@nyct.net> To: freebsd-hackers@FreeBSD.ORG Subject: Copy-on-write filesystem Message-ID: <Pine.BSF.4.05.10003031338080.1135-100000@bsd1.nyct.net>
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Upon reading of Microsoft's fabulous innovations in the filesystem arena, I started playing with some ideas of my own (not to be confused with ORIGINAL ideas) Can someone tell me why copy-on-write filesystems would be bad? 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 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). This was on a system without a ports tree, also. I think the benefits would be sexy. Copies are closer to instant. More cache hits. Space benefits. Copying /etc/skel to a user's home directory won't take up any blocks at all unless users edit their files, which, if you're an ISP, you know that 95% of users don't do anyway. There's probably a stockpile of drawbacks to this as well. Fire away. /* ---------- Michael Bacarella( mbac@nyct.net ) | (212) 293-2620 Administration / Development / Support | http://nyct.net/ [ N e w Y o r k C o n n e c t . N E T ] | info@nyct.net Bringing New York The Internet Service It Deserves! --------- */ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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