[Linux-cluster] real read-only [was Re: GFS, what's remaining]

[Pavel Machek]

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