From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Francis Moreau" Subject: Re: Which fs is a good example for learning ? Date: Tue, 6 Jan 2009 15:30:33 +0100 Message-ID: <38b2ab8a0901060630s3798ff3cvda0849e868c51e8d@mail.gmail.com> References: <20090105205945.GJ2002@parisc-linux.org> <38b2ab8a0901060046m6d47d8e4n8b968fe01c61b50b@mail.gmail.com> <20090106133654.GM2002@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org To: "Matthew Wilcox" Return-path: Received: from ug-out-1314.google.com ([66.249.92.172]:26728 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752007AbZAFOaf (ORCPT ); Tue, 6 Jan 2009 09:30:35 -0500 Received: by ug-out-1314.google.com with SMTP id 39so1540002ugf.37 for ; Tue, 06 Jan 2009 06:30:34 -0800 (PST) In-Reply-To: <20090106133654.GM2002@parisc-linux.org> Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Jan 6, 2009 at 2:36 PM, Matthew Wilcox wrote: > On Tue, Jan 06, 2009 at 09:46:04AM +0100, Francis Moreau wrote: >> That's what I think too but wasn't sure ext2 is still a good choice since it's >> pretty old and it looks like some younger fs seems to make ext2 obsolete. >> Also, it doesn't have a journal. > > This is all true. It depends what your real goal is here. If you want > to learn the fundamentals of what a filesystem has to do to get blocks > from disc and turn them into files, ext2 is perfect for your needs > since it _doesn't_ have a journal or btrees or any of that fancy stuff. > You can learn that later once you have the principles down. > If most of the fs use the same techniques as ext2 to get blocks from disk then indeed ext2 is still a good candidate. > If your goal is to learn how an advanced filesystem works, you might want > to consider looking at JFS which has journals, extents, acls, xattrs and > so on. It's around 4x as big as ext2, but then it's also about 1/3 the > size of XFS (just in terms of wc -l). It's also been properly ported > to Linux, unlike XFS which is still full of IRIXisms. OK. I'll look at JFS if I'm still motivated after looking at ext2. Thanks for the tips. -- Francis