muchomurka said:
Also you can consider to use different layout than No Resiliency volume across external disks.
Actually I decided to dump the whole idea of using Storage Spaces. After a bit more testing I discovered that I could replicate the problem in that the storage space did not work properly if the two external disks were started up in the wrong order.

If I repeated the actions in your post, then Storage space was fine till I re-booted.

I decided the benefits of Using Storage Space did not outweigh the hassle I was having. I had also bought a 4TB internal disk to help, and so I was able to change my plans completely.

Incidentally, both external disks passed Western Digital Extended Tests, and Crystal Disk Info tests so there should have been no issue from a reliability point of view.


Colin


PS I had first of all spoken to Microsoft 's help line and they told me there was nothing I could do and I'd have to format the disks. Luckily I knew enough to know that there was a solution somewhere if I could just find someone like you. Thanks again.