Background
I have a fileserver box, which currently has 2×200GB disks in lvm to give me a 400GB virtual disk. This arrangement gets good use of space, but if one disk has a failure, then the whole filesystem is trashed and cannot be recovered.
The solution is to start using raid. Before I go on, raid is not a backup solution. It cannot protect you from accidentally deleting all your files, and will not protect you from a virus or malicious user or hacker. Raid just reduces the damage if a disk happens to fail (which knowing my luck, is sometime soon).
The final solution I want is 2×500GB disks in raid1 (mirrored) with lvm on top to split into my partitions. This way I could add another pair of disks in raid, add them to the lvm and not have to worry about which partitions get new space, as lvm will allow me to expand any parition onto the new space, and have a partition across multiple disks.
Why not raid5? Raid 5 is great for getting space, as you have n+1 disks, and get the space of n disks out of it as one is the redundant disk. The problem with raid5 is it is limited to the smallest disk in the raid. So 2 500GB disks and one 200GB disk will only give 400GB as each disk can only be used up to 200GB. Raid5 is great if all your disks are the same size, but if I want to add disks, and not have to replace all 3+ disks, then with raid1 I just have to buy disks in pairs. My pc has 4 ide slots and 2 sata slots, so raid1 should be fine (disks are getting quite bit these days).
So the plan is to add 2 500GB disks. put them in raid1 with a partition for /boot (which cant be in lvm) and the rest becomes part of a lvm group, with my / and /home partitions in there (and /tmp, swap)
How I did it
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