Date: Tue, 21 Mar 2006 15:45:16 -0500 From: Kris Kennaway <kris@obsecurity.org> To: John Kozubik <john@kozubik.com> Cc: freebsd-fs@freebsd.org, jroberson@chesapeake.net, tegge@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: UFS2 Snapshots in 6.1-Beta4 - Confirmed Problems Message-ID: <20060321204516.GA21989@xor.obsecurity.org> In-Reply-To: <20060321120255.I55763@kozubik.com> References: <20060320224313.O55763@kozubik.com> <20060321184127.GA19204@xor.obsecurity.org> <20060321113923.I55763@kozubik.com> <20060321194904.GA20959@xor.obsecurity.org> <20060321120255.I55763@kozubik.com>
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--IS0zKkzwUGydFO0o Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Mar 21, 2006 at 12:07:04PM -0800, John Kozubik wrote: >=20 >=20 > On Tue, 21 Mar 2006, Kris Kennaway wrote: >=20 > > > > > This next one is complicated, and I haven't submitted a PR for it= yet, but > > > > > I believe it is quite serious for reasons I will expand on below. > > > > > > > > > > The problem is: If you completely fill a filesystem (109% usage = in `df` > > > > > on most systems) that has a snapshot on it, the system becomes ve= ry > > > > > unresponsive - all interactive and disk response lags terribly an= d, > > > > > although the system is not hung, it is in many cases unusable. > > > > > > > > Yes :-( This will probably not be fixable in time for 6.1, but > > > > hopefully it will be addressed in the future. FYI, the system may > > > > also panic in this situation. > > > > > > > > > Because my original description of this behavior was so vague, I was = going > > > to try to reproduce it again with more details, however it sounds lik= e you > > > have already witnessed this and know more about it than I do. > > > > > > Is that true ? Can I skip a few hours of trying to reproduce this ? > > > > Yes, I'm easily able to reproduce it, and I'm told that fixing it will > > require fairly extensive work & testing. >=20 >=20 > Ok. Please contact me when that testing is needed as I am happy to help. >=20 > Can I use this time to suggest that in all testing of snapshot related > issues, that multiple (preferably 4+) snapshots per filesystem are used ? > Many of the problems either do not manifest themselves, or are not as > pronounced with only one snapshot running. Yeah, I usually use 20 ;-) Kris --IS0zKkzwUGydFO0o Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (FreeBSD) iD8DBQFEIGXbWry0BWjoQKURAjX0AKCl4EAAqS6EE/JZVVdgKkDhL/CuywCffJQv XGe4rkl8R6cEkso7BSQ1j+Y= =rB17 -----END PGP SIGNATURE----- --IS0zKkzwUGydFO0o--
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