Quad sata hat - raid 5 question

Hi,

I’ve setup a quad sata hat on a raspberry pi 4B 1.2 using 4 (Seagate BarraCuda 1 TB Internal Hard Drive HDD – 2.5 Inch SATA 6 Gb/s 5400 RPM 128 MB) of these bad boys in raid 5.

I’m getting a consistent 100MB/s however I’m wondering what the bottle neck is?

Should I be getting higher speeds or is that good?

Cheers

I’ve tried 4 1TB SSDs in RAID5. The issue is that the parity calculation really stresses the CPU. It’s a limitation of the Pi’s chipset. Overclocking helps.