@softraid-support So I tried switching cables and got the same results. 5 drives slow, 4 drives fine - and it doesn’t appear to matter which 4 drives...

@softraid-support Here you go..This is with the RAID configured as a RAID 4, with all five drives selected, with the 4TB in bay 5 as the parity disk.

So with 4 x 2 TB drives configured as RAID 4 I'm getting much better performance. If I add a 5th drive to the mix it falls over. And it doesn't seem...

Here you go.. Here's with 5 disks configured as RAID 5, and then 5 disks as RAID 4. Just about to reconfigure it as a RAID 4 with 4 drives