Best answer
Yes that's absolutely correct. RAID 1 is a mirror and requires at least 2 drives, so as they mentioned if one drive fails you're still online with the other drive still functional, as a result you also see increased performance as data is read from either of the 2 drives. RAID 1 is however limiting in that you can only use 50% capacity of your drives (or 100% of a single drive), for example if you have 2 x 2TB disks you get 2TB usable capacity.
RAID 0 stripes data - So same as RAID 1 it offers a performance boost as data is stored on both drives, there is no mirroring so you get the full usable space of both disks (2 x 2TB would get 4TB usable on RAID 0). However again what they said is correct, if one of the drives fails under RAID 0, you lose all data on that server.
