Date: Mon, 19 Jan 2004 22:26:01 +0000 From: Scott Mitchell <scott+freebsd@fishballoon.org> To: freebsd-current@FreeBSD.org Subject: vn vs. md - persistent swap-backed memory disk? Message-ID: <20040119222601.GB572@tuatara.fishballoon.org>
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Hi all, On 4.whatever, I can create a swap-backed vn(4) disk that will survive a reboot, following the recipe in the vnconfig manpage. All very useful for stuff in /tmp that I don't _really_ care about, but it's nice to have hang around anyway. The equivalent setup on a 5.2 box with md(4) doesn't behave in quite the same way: # mdconfig -a -t swap -o reserve -s 1g -u 1 # newfs -U /dev/md1 [...] # mount /dev/md1 /tmp # umount /tmp # mdconfig -d -u 1 # mdconfig -a -t swap -o reserve -s 1g -u 1 # mount /dev/md1 /tmp mount: /dev/md1 on /var/tmp: incorrect super block Same result if I don't use the 'reserve' flag, or if I bsdlabel md1 and mount md1c instead. I _can_ recover a filesystem on a file-backed md though. So just wondering if it's supposed to work this way, or if I'm doing something wrong setting it up? Scott -- =========================================================================== Scott Mitchell | PGP Key ID | "Eagles may soar, but weasels Cambridge, England | 0x54B171B9 | don't get sucked into jet engines" scott at fishballoon.org | 0xAA775B8B | -- Anon
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