From owner-freebsd-current@FreeBSD.ORG Wed Jun 4 23:30:06 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id CE3C337B401 for ; Wed, 4 Jun 2003 23:30:06 -0700 (PDT) Received: from kurims.kurims.kyoto-u.ac.jp (kurims.kurims.kyoto-u.ac.jp [130.54.16.1]) by mx1.FreeBSD.org (Postfix) with ESMTP id E306143F3F for ; Wed, 4 Jun 2003 23:30:04 -0700 (PDT) (envelope-from garrigue@kurims.kyoto-u.ac.jp) Received: from localhost (suiren.kurims.kyoto-u.ac.jp [130.54.16.25]) by kurims.kurims.kyoto-u.ac.jp (8.9.3p2/3.7W) with ESMTP id PAA13192 for ; Thu, 5 Jun 2003 15:30:02 +0900 (JST) To: freebsd-current@freebsd.org X-Mailer: Mew version 1.94.2 on Emacs 21.2 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20030605153002C.garrigue@kurims.kyoto-u.ac.jp> Date: Thu, 05 Jun 2003 15:30:02 +0900 From: Jacques Garrigue X-Dispatcher: imput version 20000228(IM140) Lines: 34 Subject: Critical problems with md on 5.0-RC1 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 Jun 2003 06:30:07 -0000 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 JG