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I've just restarted my computer which was building up a RAID5 for the first time. This of course meant that my computer had to rebuild the whole thing from ground up.

Before I restarted the computer I've had already set up a file system, which cannot be found anymore.

So: Does building up the RAID (again) overwrite any information placed on the volume?

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It would be useful to know what exactly you are trying to do. For example, are you using LVM on top of RAID or the other way around? – JanC Oct 25 '10 at 20:48
I'm combining 3 disks directly into a RAID, so there's no LVM at this level. I was just wondering, if the re-rebuilding of the RAID was messing with the data I already put on the created raid. – Georg Schölly Oct 25 '10 at 21:23
Can you include the output of /proc/mdstat too? – Kees Cook Oct 26 '10 at 18:44
@kees:, though I don't why that's important to the question. – Georg Schölly Oct 26 '10 at 19:46
Does sudo blkid /dev/md0 say anything about that volume? – Kees Cook Oct 27 '10 at 5:49

It's best not to reboot your system until after the initial RAID sync has finished, but you should be able to create your LVM physical volumes (pvcreate /dev/md0 etc). If you've already done this and they're not showing up, it's possible that on restart the system did not auto-start your RAID due to it being out of sync. If you RAID is running correctly, you should be able to manually restart your LVM with sudo vgchange -a y at which point the LVs should be visible again with sudo lvs.

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I've learned that the hard way. :) The command is vgchange -a y, but that didn't work. – Georg Schölly Oct 26 '10 at 19:47

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