Date: Sun, 21 Mar 2010 10:09:19 +0000 From: Mike Clarke <jmc-freebsd2@milibyte.co.uk> To: freebsd-questions@freebsd.org Cc: Modulok <modulok@gmail.com> Subject: Re: Copying mirrored partitions - will this work? Message-ID: <201003211009.19888.jmc-freebsd2@milibyte.co.uk> In-Reply-To: <64c038661003201848o1379a891t680593cf3594b7b0@mail.gmail.com> References: <201003201532.48793.jmc-freebsd2@milibyte.co.uk> <64c038661003201848o1379a891t680593cf3594b7b0@mail.gmail.com>
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On Sunday 21 March 2010, Modulok wrote: > On 3/20/10, Mike Clarke <jmc-freebsd2@milibyte.co.uk> wrote: [snip] > > I have two 500GB disks, /dev/ad4 and /dev/ad8, each partitioned > > into 4 slices of 88, 88, 42 and 259GB. My system is installed on > > the first slices (ad4s1 and ad8s1) which are mirrored as > > /dev/mirror/gm0. The second slices (ad4s2 and ad8s2) are currently > > unused. My thoughts are to temporarily add ad4s2 into gm0 with > > "gmirror insert gm0 ad4s2" and wait for the mirror to synchronise. > > I should then be able to remove the temporary addition with > > "gmirror remove gm0 /dev/ad4s2" at which point ad4s2 should be a > > duplicate of the original system and I can then go ahead and create > > a new mirror with "gmirror label -b load gm1 ad4s2" and "gmirror > > insert gm1 ad8s2". After editing /etc/fstab in the new mirror to > > use gm1 instead of gm0 I should then be able to boot into the > > system on slice 2 and upgrade it to STABLE while still keeping my > > original system to fall back to if required. > How valuable is your data? In financial terms not very, but still valuable enough to not want to lose it. > I recommend you make an offline backup. Yes, I take regular backups but regard them as the "emergency parachute" and prefer to not put myself in a position where I'm doing something risky and the backup files are the only protection, so I'll be making additional backups anyway. > There's a lot of steps in > your procedure which introduce room for error. Yes, it's a bit of unknown territory for me but with 6 partitions on the slice it does require fewer potentially dangerous manual steps (like newfs or restore to the wrong device) so looks like an interesting experiment. > You could perhaps > disconnect one of the hard drive's data cable (same thing). Also, > make a backup copy of your geom meta data somewhere. That's a possibility to consider but would result in additional changes to the mirror configuration, something I'd prefer to keep to a minimum. -- Mike Clarke
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