First 15 drives (a natural RAID6 set)
Backblaze holds 45 internal SATA disks. We decided to arrange them in groups of 15 drives (neatly matching the SATA controllers as well as the interior physical layout).
Our unit has three "sets" of 15 disk drives, configured with Linux Software RAID6
The RAID6 LUNS are aggregated via Linux LVM and the XFS filesystem is placed on top.