From owner-freebsd-fs Thu Sep 21 8:19: 4 2000 Delivered-To: freebsd-fs@freebsd.org Received: from mail.clarkson.edu (mail.clarkson.edu [128.153.4.10]) by hub.freebsd.org (Postfix) with SMTP id D743037B43C for ; Thu, 21 Sep 2000 08:19:01 -0700 (PDT) Received: (qmail 1112 invoked by uid 0); 21 Sep 2000 15:18:56 -0000 Received: from sc-1-459.sc.clarkson.edu (HELO clarkson.edu) (128.153.23.68) by mail.clarkson.edu with SMTP; 21 Sep 2000 15:18:56 -0000 Message-ID: <39CA26D7.51D314BF@clarkson.edu> Date: Thu, 21 Sep 2000 11:18:47 -0400 From: Dwight Tuinstra X-Mailer: Mozilla 4.75 [en] (X11; U; FreeBSD 4.1-RELEASE i386) X-Accept-Language: en MIME-Version: 1.0 To: freebsd-fs Subject: Re: Journaling Filesystems in bsd? (LFS, anyone?) References: <9164771DDCABD3118333005004E9446E204774@mother.netcentralen.dk> <20001222152532.B97883@roaming.cacheboy.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Adrian Chadd wrote: > > On Thu, Sep 21, 2000, Michael Aronsen wrote: > > Hello > > Just wanted to know if there are any projects to get something like reiserfs > > to FreeBSD? > > There's a few ideas floating around but noone has provided anything > concrete. > > You're more than welcome to start something more concrete. :-) I'm interested in porting an alternative file system to FreeBSD. As a long-term graduate research project, I've been looking into the code for LFS (Log-structured File System) on NetBSD. Such a system is optimized for many small writes, and given the amounts of RAM available for read caches nowadays, should deliver read performance comparable (or not much worse) than FFS. Additionally, LFS should provide better and faster crash recovery than either FFS or journaling file systems. In a nutshell, the difference between journaling file systems and LFSes is that jFSes keep a log of metadata, whereas an LFS keeps metadata AND data in a unified log structure (and yes, this means playing lots of tricks with how inodes are located and found). At present, the only working, available LFS system (that I'm aware of) for a freeNIX is the one in NetBSD, though there are at least two efforts underway for Linux. There is an order of magnitude improvement in the write times for their "pkgsrc" directory (equivalent to the FreeBSD "ports" directory) when comparing FFS to LFS. The NetBSD LFS code is still beta, but in pretty good working order. There has been controversy regarding the performance claims of LFS under various disk activity patterns. The research I'll be doing aims to investigate the claims, especially after implementing the optimizations proposed by Matthews et al (Improving the Performance of Log-Structured File Systems With Adaptive Methods; Proc. Sixteenth ACM Symposium on Operating System Principles). Dr. Matthews is my advisor on this research. Is there any interest in porting/redesigning LFS for FreeBSD? --Dwight Tuinstra tuinstra@clarkson.edu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message