Date: Mon, 24 Jan 2005 12:13:38 -0800 From: Danny Howard <dannyman@toldme.com> To: freebsd-questions@freebsd.org Subject: FreeBSD HOWTO: Software Mirror System Disk Message-ID: <41F556F2.4020503@toldme.com>
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[ From http://dannyman.toldme.com/2005/01/24/freebsd-howto-gmirror-system/ ] A new feature of FreeBSD 5.3 is the ability to set up a software mirror of your system disk. This allows you to boot off either of a pair of hard disks, which will then function as a RAID1, which will ensure system uptime in the face of a single disk failure. As the documentation is a bit sketchy, here’s a quick cheat sheet for setting this up with gmirror: (This crib sheet assumes you have a pair of identical IDE (in my case, SATA) drives identified as ad4 and ad6.) 1. Install FreeBSD on to ad4. 2. Reboot with the Install CD. 3. Enter Fixit mode, using Install CD disc2 as the “live filesystem” 4. # *chroot /dist* # *mount_devfs devfs /dev* # *gmirror label -v -b round-robin gm0 /dev/ad4* # *gmirror insert gm0 /dev/ad6* # *mount /dev/mirror/gm0s1a /mnt* # *echo ‘geom_mirror_load="YES"‘ >> /mnt/boot/loader.conf* # *echo ’swapoff="YES"‘ >> /mnt/etc/rc.conf* 5. Edit /mnt/etc/fstab to convert ad4 -> mirror/gm0 6. Reboot Thanks to the few dozen people who have come before me, and posted crucial hints to the mailing lists. Thanks also to Ralf S. Engelschall who has a far more verbose explanation of how to do this sort of thing with mis-matched disks. [See http://people.freebsd.org/~rse/mirror/ ] <http://people.freebsd.org/%7Erse/mirror/>; You should definately look over the gmirror man page, and review the output of *"gmirror list gm0"* when swapping out drives. You can disable automatic rebuild, etc. It is quite nice. Sincerely, -danny
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