I've currently got 4x 1TB sata drives in raid5. However, I'm looking to expand further and (try) and improve performance by having (eventually) 4x 2TB drives.
My question is, because I don't want to fork out for 4 drives at once, has anyone experience of using a configuration similar to 2x 2TB drives in raid0 mirrored against my existing 4x 1TB drives in raid0? In theory that should work, no?
That should work with Linux software RAID yeah. You may want to drop the mirror and just create RAID0's, using one for backup. That would still be quite safe, protected from most dangers. You still rely on the same RAID layer for access to your data though.
By the way, don't you want to try out ZFS? If you don't know yet, you should read up (on wikipedia) on what ZFS is and why it's so great.