Since I may move to some other country and that I’d like my server to be a bit more tolerant wrt. disks crashes, I thought about having my FreeBSD system installed on a gvinum mirror.
After some nice readings like this one, it seemed to me that there was no easy way to do it.
As usual, when I don’t find a satisfactory way to do what I want, I poke random people on IRC, hopefully there was at least one GEOM guru (Pawel Jakub Dawidek, pjd) who told me to ask Lukas Ertl (le). What follows is the discussion I had some minutes ago with Lukas.
16:12 -!- Irssi: Starting query in EFNet with le
16:12 <le> so, you want to mirror /, right?
16:12 <flz> yup
16:13 <le> ok, install on disk 1 as usual, with out vinum
16:14 </le><le> once finished, bsdlabel disk 2, so that it looks like this:
16:14 </le><le> a: 614400 281 4.2BSD 0 0 0
16:14 </le><le> c: 142253248 0 unused 0 0 # "raw" part, don't edit
16:14 </le><le> d: 142253232 16 vinum
16:14 </le><le> first create the 'd' partition, but not 'a'
16:14 </le><le> then create the vinum volumes on disk 2
16:15 <flz> looks like the same trick there's on the webpage i specified, nope ?
16:15 <le> when you're done with the vinum volumes, add the 'a' partition as shown above, with the correct size of course
16:15 <flz> 281 seems a recurring number 
16:15 <le> size of 'a' must match the size of your 'root' vinum volume
16:15 </le><le> the 281 offset is important, of course
16:16 </le><le> don't forget to keep an offset of at least 16 for 'd'
16:16 <flz> k
16:16 <le> and don't forget to add a boot loader to disk 2
16:16 </le><le> once your done with that, reboot and bring up the machine on the vinum volumes (i.e., boot from disk 2)
16:16 <flz> yup
16:17 <le> then you clean up disk1 and create the second half of your mirror there
16:17 </le><le> that's all
16:17 </le><le> more or less what's on the webpage, maybe some details are not the same anymore
16:17 </le><le> but that's it
[...]
16:18 </le><le> the important part is that you get the volumes on disk2 working
16:18 </le><le> once you were able to boot from disk2 (the vinum volumes), you're set
16:19 </le><le> if you run into problems, let me know, i'd like to hear your experiences
16:19 </le><le> plus, it's a good test in case there are bugs
[...]
16:21 </le><le> the webpage mentioned describes a different kind of bsdlabel setup
16:22 </le><le> basically, it should allow you to boot the disks even if vinum is broken, by duplicating the volume structures in simple bsdlabel offsets
16:22 </le><le> i never tried that
16:22 </le><le> and it could be that you run into trouble with that
16:22 </le><le> geom doesn't like overlapping partitions very much
16:23 </le><le> anyway, let me know how it goes
</le></flz></le></flz></le></flz></le></flz></le></flz></le>
Nothing much to add, if somebody test this before me (that means within 2 weeks), don’t hesitate to poke with comments or trouble reports.
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