Date: Tue, 16 Jan 2007 21:26:47 +0100 From: Willem Jan Withagen <wjw@withagen.nl> To: Doug Ambrisko <ambrisko@ambrisko.com> Cc: Scott Oertel <freebsd@scottevil.com>, Willem Jan Withagen <wjw@digiware.nl>, freebsd-stable@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: running mksnap_ffs Message-ID: <45AD3507.402@withagen.nl> In-Reply-To: <200701161934.l0GJY1mh057095@ambrisko.com> References: <200701161934.l0GJY1mh057095@ambrisko.com>
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Doug Ambrisko wrote: > | > or things can get wedged. We have some other patches as well that might > | > be required. As a hack on a local server we have been using snap shots > | > to do a "hot" back-up of a data base each morning. This is based on > | > 6.x. > | > | What do you mean by "get wedged"? Are you seeing a deadlock, and if > | so then what are the details? When you say 6.x, do you mean > | up-to-date RELENG_6? There were various snapshot deadlock fixes > | committed over the past year including some in the past few months. > > 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. Getting the file system back is only thru "hard reboot". Trying to do it the gentle way locks the whole system. I'm refering further testing and trying until I have more time to upgrade to 6.2-RELEASE and put some of the debug options in the kernel. On the otherhand is this my main fileserver. So testing too much is sort of dangerous, and running a fsck on 1.5T is very tedious. --WjW
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