Configure starting format for btrfs cache arrays

[kode54]

This would be useful for cases where redundancy of the data is not needed, but compounding the space of multiple drives is.

 

The suggested options would be:

 

Data as RAID1: Wanted redundancy, although true backup is probably a way better idea.

Data as RAID0: Redundancy not wanted, and all drives are 100% identical in size.

Data as single: Drives are unbalanced in size, utilize all available space for data.

 

Metadata should always be RAID1, though, so there's at least two copies of it floating around in the volumes.