Date: Thu, 30 Mar 2000 00:49:55 +0200 From: "Karsten W. Rohrbach" <karsten@rohrbach.de> To: Bruce Evans <bde@zeta.org.au> Cc: "Mark W. Krentel" <krentel@dreamscape.com>, freebsd-fs@FreeBSD.ORG, kwc@world.std.com Subject: Re: ext2fs optional features Message-ID: <20000330004955.B24631@rohrbach.de> In-Reply-To: <Pine.BSF.4.21.0003251849470.522-100000@alphplex.bde.org>; from bde@zeta.org.au on Sat, Mar 25, 2000 at 09:27:28PM %2B1100 References: <200003250310.WAA00537@dreamscape.com> <Pine.BSF.4.21.0003251849470.522-100000@alphplex.bde.org>
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Bruce Evans(bde@zeta.org.au)@Sat, Mar 25, 2000 at 09:27:28PM +1100: > On Fri, 24 Mar 2000, Mark W. Krentel wrote: [...] > > > > What are the optional features? What does "sparse_super" do? > > They are extensions that modify the filesystem format. I don't know > exactly what "sparse_super" does. FreeBSD's ext2fs knows even less. > AFAIK sparse_super is just a different density of super block backups on your block device. in the old ext2fs version you had plenty of SB backup copies on your fs which leads to slow mounting, etc., if your run for example on a RAID which has a large fs on it so you got thousands of SB copies to check (and of course update if you modify the SB). i guess tytso revamped these structures a little bit to optimize the fs to news servers since you got large spool areas on them... support was added in the 2.1.x kernels and is told to be stable in 2.2.x. more information could be in the e2fsutils package -- there are some other optimizations as well, for example storing a mime-type with the file metadata (this was not used yet i think, but since there is webfs -- a http server in a nfs export vfs manner -- this option will become more important. > > Does Linux actually use these features, or are they for future use? > > Linux has supported the ext2fs "filetype" and "sparse_super" features > for several years. Otherwise, they wouldn't be the default for the > current version of mkfs.ext2fs. > > > Is it possible to support R/W mounts with these features? > > Everything is possible in software :-). > ...if there actually _are_ changelogs in place ;-) source code management is not one of linux's strong points... /k -- > knowledge is power. power corrupts. study hard, be evil http://www.webmonster.de http://www.apache.de http://www.splatterworld.de (NIC-HDL KR433/KR11-RIPE) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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