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Date: Fri, 09 Sep 2011 08:20:17 +0200
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From: Oliver Lehmann <lehmann@ans-netz.de>
To: current@freebsd.org, pjd@FreeBSD.org
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Subject: gmirror: how to make your system reboot
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Hi,

shouldn't there be a failsafe to not be able to destroy the
gmirror as long as it is still in use like mounted?

1. create a gmirror with n>=1 disks
2. newfs the gmirror device
3. mount the gmirror device
4. remove all disks from the gmirror
5. system reboots (gmirror gone but still mounted)

nudel# gmirror status
nudel# gmirror label -b prefer test /dev/ada1p2
nudel# newfs /dev/mirror/test
/dev/mirror/test: 4096.0MB (8388600 sectors) block size 32768,  
fragment size 4096
         using 6 cylinder groups of 740.00MB, 23680 blks, 47360 inodes.
super-block backups (for fsck -b #) at:
  192, 1515712, 3031232, 4546752, 6062272, 7577792
nudel# mount /dev/mirror/test /mnt/tmp
nudel# gmirror remove test ada1p2
<reboot>


> uname -a
FreeBSD nudel.salatschuessel.net 9.0-BETA2 FreeBSD 9.0-BETA2 #0: Thu  
Sep  8 19:59:40 CEST 2011      
olivleh1@nudel.salatschuessel.net:/usr/obj/usr/src/sys/GENERIC  amd64
>

I'm just having remote access right now to the system so I'm not able
to provide any dumps but the system instantly reboots.