Subject: Re: LFS partition limitations
To: Tracy J. Di Marco White <email@example.com>
From: Manuel Bouyer <firstname.lastname@example.org>
Date: 10/03/2000 21:30:26
On Tue, Oct 03, 2000 at 01:00:16PM -0500, Tracy J. Di Marco White wrote:
> My husband thought it would be better. He's started using one of the
> Linux journaling filesystems on his laptop, and his reasoning was such
> that given the testing he's doing, he ends up power cycling it semi
> regularly, he figured that the journaling file system would leave him
> much less vulnerable to corruption.
true, because Linux/ext2fs doesn't have any protection against this kind of
evenement. This is because on linux it's mounted async (by default; you can
also mount it sync but performances are abyssal), on NetBSD ext2fs is as
reliable as FFS because metadata writes are synchronous (or async but ordered
with softdep). You can power-cycle a NetBSD/FFS system without harm, it
will always come up properly and you won't loose files. I've yet to see a
NetBSD system requiring a manual fsck after an unclean shutdown (other than
because of hardware issues). I have a small web server (running several mrtg
instances, so filesystem write activity is not null) which I never halt,
although we regulary have power shutdowns (planned or not :). It's running
reliably for more than 20 months now. I also have linux clients on this
network, and after each power failure there are filesystems issues.
> }From people working with True64 or irix, it's worse because Digital or SGI
> }doesn't provide a tool to repair the fs is something got really from.
> I work with Tru64, and I've been running ADVfs for more than 3 years on
> multiple systems with no problems. So I haven't had to repair the FS.
> }At last with LFS we have a fsck. But I would still trust better ffs, even
> }when the known LFS bugs will be corrected.
> I had thought to use FFS+softdep, but my husband thought a journaling
> filesystem would be much safer. I wanted to use NetBSD on it, and so
> I proposed LFS. compromise. I'm really not that knowledgeable about
> what a log/journal based file system would gain you.
You don't need a journaling filesystem to have something reliable, I think
a properly implemented (that is, not linux+ext2fs) FFS is better, especially
in face of SW bugs or hardware failures. For unclean shutdowns, it's as
good as a journaling filesystem, but you need an fsck before mounting R/W
(which can sometime be a gain :).
Manuel Bouyer <email@example.com>