Date: Fri, 09 Sep 2005 07:30:37 -0500 From: Eric Anderson <anderson@centtech.com> To: freebsd-geom@freebsd.org Subject: GEOM_FOX? Message-ID: <4321806D.5010105@centtech.com>
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What's the status on GEOM_FOX? This is very interesting to me, as I have a lot of fiber channel/SAN backend now, and would like to utilize multiple paths with FreeBSD. Eric Here's a note I found from phk@: --------------------------------------------------------------------- I have just committed the GEOM_FOX class, see commit message below. GEOM_FOX is named after the common red fox, which amongst other traits have a liking for having multiple exits from its den. GEOM_FOX will recognize a magic label on the device, and all devices which come up with the same label will be assumed to be independent paths to the same underlying physical device. The first device found will name the created redundant device (I need to work on that aspect because it makes the name a bit unpredicatable right now). If the currently used path to the device fails, GEOM_FOX will switch to another path and retry the operation. For anyone who wants to play with this, the following shell script could be a beginning. It exploits the fact that the same file can be used to back several MD(4) devices, so you need no special hardware. This will probably be most interesting for people with FibreChannel/SAN hardware, but since the isp driver has very aggresive retrie policies as it is now, the actual usability is still somewhat below par. I'm sure both mjacob an I would appreciate any help we can get in fixing this. #!/bin/sh set -ex # cleanup mdconfig -d -u 10 > /dev/null 2>&1 || true mdconfig -d -u 20 > /dev/null 2>&1 || true kldunload geom_fox > /dev/null 2>&1 || true # Create a 4M disk image dd if=/dev/zero of=fox.img bs=1k count=4096 # create a "disk" on it. mdconfig -a -t vnode -f fox.img -u 10 # Put the GEOM::FOX label on it echo "GEOM::FOX test-fox" | dd of=/dev/md10 conv=sync # load the geom_fox module kldload geom_fox # add another path mdconfig -a -t vnode -f fox.img -u 20 # remove it again mdconfig -d -u 20 # add it again mdconfig -a -t vnode -f fox.img -u 20 # remove the original path mdconfig -d -u 10 # add it again mdconfig -a -t vnode -f fox.img -u 10 # newfs the "fox" newfs /dev/md10.fox # fsck it fsck_ffs /dev/md10.fox # remove the currently primary path mdconfig -d -u 20 # fsck it again fsck_ffs /dev/md10.fox # add a new secondary path mdconfig -a -t vnode -f fox.img -u 30 # remove the primary mdconfig -d -u 10 # fsck it again fsck_ffs /dev/md10.fox # Remove the primary and only path mdconfig -d -u 30 # See what's left (hopefully nothing) ls -l /dev/md* -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------
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