Date: Tue, 21 Mar 2006 12:07:04 -0800 (PST) From: John Kozubik <john@kozubik.com> To: Kris Kennaway <kris@obsecurity.org> Cc: freebsd-fs@freebsd.org, jroberson@chesapeake.net, tegge@freebsd.org Subject: Re: UFS2 Snapshots in 6.1-Beta4 - Confirmed Problems Message-ID: <20060321120255.I55763@kozubik.com> In-Reply-To: <20060321194904.GA20959@xor.obsecurity.org> References: <20060320224313.O55763@kozubik.com> <20060321184127.GA19204@xor.obsecurity.org> <20060321113923.I55763@kozubik.com> <20060321194904.GA20959@xor.obsecurity.org>
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On Tue, 21 Mar 2006, Kris Kennaway wrote: > > > > 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 very > > > > unresponsive - all interactive and disk response lags terribly and, > > > > 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 like 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. Ok. Please contact me when that testing is needed as I am happy to help. 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. Thanks. ----- John Kozubik - john@kozubik.com - http://www.kozubik.com
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