4 x SSD Btrfs/EXT4 RAID Tests On Linux 4.15

Using the high-end SilverStone TS421S 4-disk SATA drive enclosure, I've been carrying out a number of Btrfs and EXT4 file-system multi-disk benchmarks over the past week. Here are the latest numbers for how Btrfs' native RAID capabilities are running up against EXT4 when using MDADM "soft" RAID.