Date: Sun, 1 Oct 2000 02:17:17 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: karsten@rohrbach.de Cc: mbendiks@eunet.no (Marius Bendiksen), des@ofug.org (Dag-Erling Smorgrav), tuinstra@clarkson.edu (Dwight Tuinstra), freebsd-fs@FreeBSD.ORG (freebsd-fs) Subject: Re: Journaling Filesystems in bsd? (LFS, anyone?) Message-ID: <200010010217.TAA18354@usr05.primenet.com> In-Reply-To: <20001001040520.D83678@rohrbach.de> from "Karsten W. Rohrbach" at Oct 01, 2000 04:05:20 AM
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Karsten writes: > Marius Bendiksen(mbendiks@eunet.no)@Mon, Sep 25, 2000 at 02:40:21PM +0200: > [...] > > more proper such filesystem. Or, get someone to port WAFL, and get NVRAM. > > this would be an interesting thing. with all the negative points of > nvram you got a few good points in wafl design which might be of > interest when it comes to lots of disks carrying one filesystem: > a) metadata is contained in files > b) those files are successors, referenced by the last on-volume snap > c) spreading the file system over a bunch of disks is easy, also without > lvm by design > d) devices in a bunch can be different size > e) you can hot-grow the filesystem (if your hardware supports hot-plug) > f) you can have as many files as you wish (or limit in your hashing > structure) on a volume > g) linear write window over all devices > > is netapp's wafl concept patented somehow? There are three patents of which I'm aware. That said, someone has already written a read-only WAFL FS for FreeBSD; it was announced to the FreeBSD FS list several weeks ago. Another interesting concept is described in: The Design and Implementation of a DCD Device Driver for UNIX Tycho Nightengale, Yiming Hu, Qing Yang 1999 Usenix <http://www.usenix.org/events/usenix99/full_papers/nightingale/nightingale_html/>; Ignore the fact that Jordan and I are thanked for a tiny amount of information at the end of the paper: it's a very good paper, anyway. ;^) Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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