So, currently I have 6 14TB drives in hardware RAID 6 in a 12-bay server (around 50TB usable space iirc). I'm really debating pulling the trigger on a bunch of those 20TB drives on sale at Best Buy right now. With how many I'm thinking about getting, there wouldn't be enough free drive slots to set up the new drives at the same time as the current ones and then transfer them over. What's the best way to set up a completely new array of drives on the same machine and transfer all of my data? Would I basically have to set up a third set of drives on a NAS somewhere and copy my data from my main machine to there, then set up the new drives in RAID and then copy my data back from the NAS to the new RAID array?
Also, what would be the best program to do that? I've been using rsync to run backups onto some other drives in the machine, but if I want to clone the entire drive I assume something else might be better.
Edit: Of note, I actually have most of the data from the RAID array backed up on drives in 5 of the other 6 slots. Unless you think I'll need to back up more data than rsync can copy, it should be quick to update that if using a third set of drives is the only solution
Bonus topic: Convince me why I should switch from RAID 6. RAID 10 seems like a colossally inefficient use of drives (esp. since you can still lose the array if 2 fail, theoretically) and the chances of two drives failing during a rebuild in RAID 6 seems pretty unlikely. I like the read speed increase from striping that RAID provides.