Date: Tue, 16 Jan 2007 21:55:00 +0100 From: Willem Jan Withagen <wjw@withagen.nl> To: Kris Kennaway <kris@obsecurity.org> Cc: freebsd-stable@freebsd.org, Scott Oertel <freebsd@scottevil.com>, Willem Jan Withagen <wjw@digiware.nl> Subject: Re: running mksnap_ffs Message-ID: <45AD3BA4.8090505@withagen.nl> In-Reply-To: <20070116203739.GA343@xor.obsecurity.org> References: <200701161934.l0GJY1mh057095@ambrisko.com> <45AD3507.402@withagen.nl> <20070116203739.GA343@xor.obsecurity.org>
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Kris Kennaway wrote: ...... >>> The file-system would come to a stop, processes stuck on bio, snap-shots >>> not finishing etc. This was caused by the system running out of usable >>> buffers. The change forces them to be flushed every so often. This is >>> independant of locking. 10 might be to aggresive. Some scaling of >>> nbuf would probably be better. >> When I run mksnap_ffs it runs to the point where ANY access to the >> filesystem gives that process a lockup. > > Yes, that is expected. Actually it begins when something accesses the > directory in which the snapshot is being made, since that causes the > parent directory to be locked...then something tries to access the > parent directory, which eventually cascades back to the root. > >> Getting the file system back is only thru "hard reboot". Trying to do it >> the gentle way locks the whole system. > > Or waiting until the snapshot operation finishes. You (still) haven't > determined that it's actually hanging as opposed to just waiting for > the snapshot operation to finish. True, and that is what I was refering to. * I've let it run for 12 hours on 1,5T (that's why I asked for other experiences) * I looked at diskstats with gstat: that turned out that everything was idle for > 5 minutes Then I concluded that it was locked. IF you can give me a fair estimate of time < 1 day I'll be willing to let it sit for so long. But I'm not going to wait forever. :) --WjW
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