From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: real read-only [was Re: GFS, what's remaining] Date: Mon, 5 Sep 2005 10:27:35 +0200 Message-ID: <20050905082735.GA2662@elf.ucw.cz> References: <20050901104620.GA22482@redhat.com> <20050901035939.435768f3.akpm@osdl.org> <1125586158.15768.42.camel@localhost.localdomain> <20050901132104.2d643ccd.akpm@osdl.org> <20050903051841.GA13211@redhat.com> <20050904203344.GA1987@elf.ucw.cz> <20050905055428.GA29158@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: To: Theodore Ts'o , David Teigland , Andrew Morton , Alan Cox , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-cluster@redhat.com Content-Disposition: inline In-Reply-To: <20050905055428.GA29158@thunk.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Hi! > > > - read-only mount > > > - "specatator" mount (like ro but no journal allocated for the mount, > > > no fencing needed for failed node that was mounted as specatator) > > > > I'd call it "real-read-only", and yes, that's very usefull > > mount. Could we get it for ext3, too? > > This is a bit of a degression, but it's quite a bit different from > what ocfs2 is doing, where it is not necessary to replay the journal > in order to assure filesystem consistency. > > In the ext3 case, the only time when read-only isn't quite read-only > is when the filesystem was unmounted uncleanly and the journal needs > to be replayed in order for the filesystem to be consistent. Yes, I know... And that is going to be a disaster when you are attempting to recover data from failing harddrive (and absolutely do not want to write there). There's a better reason, too. I do swsusp. Then I'd like to boot with / mounted read-only (so that I can read my config files, some binaries, and maybe suspended image), but I absolutely may not write to disk at this point, because I still want to resume. Currently distros do that using initrd, but that does not allow you to store suspended image into file, and is slightly hard to setup. Pavel -- if you have sharp zaurus hardware you don't need... you know my address