From owner-freebsd-fs Sat Mar 25 2:27:58 2000 Delivered-To: freebsd-fs@freebsd.org Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16]) by hub.freebsd.org (Postfix) with ESMTP id 96E9037B61A for ; Sat, 25 Mar 2000 02:27:54 -0800 (PST) (envelope-from bde@zeta.org.au) Received: from bde.zeta.org.au (bde.zeta.org.au [203.2.228.102]) by mailman.zeta.org.au (8.8.7/8.8.7) with ESMTP id VAA14626; Sat, 25 Mar 2000 21:35:40 +1100 Date: Sat, 25 Mar 2000 21:27:28 +1100 (EST) From: Bruce Evans X-Sender: bde@alphplex.bde.org To: "Mark W. Krentel" Cc: freebsd-fs@FreeBSD.ORG, kwc@world.std.com Subject: Re: ext2fs optional features In-Reply-To: <200003250310.WAA00537@dreamscape.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Fri, 24 Mar 2000, Mark W. Krentel wrote: > ... > And this is what appears in the logs: > > Mar 24 21:36:47 blue /kernel: WARNING: R/W mount of dev 0x3040a > denied due to unsupported optional features > > 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. > 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 :-). > I remember 3.4-release let me mount the same filesystem R/W. Was I That was a bug in 3.4 :-). > unknowingly corrupting the filesystem, or running some risk of a panic? The "filetype" extension caused panics. I don't know what the "sparse_super" extension caused. > I noticed that tune2fs also reported: > > Block size: 4096 > Fragment size: 4096 > > Does Linux really not support fragments?? I was stunned. Fragments are a dubious feature. They were more useful when 100MB disks were large. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message