Hello @tothemoon ,
Welcome to the forum!
Since you already have a sdb1, I would recommend to format it to ext4 and use it in the fstab
We recommend to do not use RAID (or LVM) if you plan to use this system only for Storj, it’s not required and unlikely would have a ROI. See RAID vs No RAID choice
If you do decide to use LVM, please, do not use the stripe ability of this disk manager - with one disk failure the whole node will be lost. The better approach is to use one disk per node.