Date: Thu, 05 Jun 2003 15:30:02 +0900 From: Jacques Garrigue <garrigue@kurims.kyoto-u.ac.jp> To: freebsd-current@freebsd.org Subject: Critical problems with md on 5.0-RC1 Message-ID: <20030605153002C.garrigue@kurims.kyoto-u.ac.jp>
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There is a very serious problem in the md filesystem, since at least
5.0-RELEASE, and it is not yet fixed.
You can see details of the problem at
http://www.freebsd.org/cgi/query-pr.cgi?pr=47538
Since this problem may result in data corruption, I believe that at
least there should be a warning in the release notes about NOT using a md
filesystem for /tmp. Lots of people seem to do that.
Short description (assuming 256M of machine memory, and about 230M of
data in /usr/X11R6/lib):
mdmfs -s256M /dev/md0 /mnt
tar cf - -C /usr/X11R6 | tar xf - -C /mnt
diff -r /usr/X11R6/lib /mnt/lib
And you start seeing the differences...
Apparently some sectors are just zeroed. File size does not change.
Pretty hard to detect.
Anothere problem I have is that md on a vnode in an msdos partition
doesn't work. I have been using it to get extra disk space on a
laptop. In 5.0-RELEASE the system just froze, now the file system
starts refusing to sync while unpacking a big archive with unzip.
As a conclusion, two of my favorite features since FreeBSD-2.2, namely
memfs and vn, are currently broken. I suppose that one has to wait a
bit after an hostile takeover :-)
Cheers,
---------------------------------------------------------------------------
Jacques Garrigue Kyoto University garrigue at kurims.kyoto-u.ac.jp
<A HREF=http://wwwfun.kurims.kyoto-u.ac.jp/~garrigue/>JG</A>;
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