I've totally rebuild the NAS now, to stock 1.75. That didn't go without problem either so perhaps there was some underlying disk problem. Disks have been erased, reformated and the stock firmware reflashed (from emergency mode) so hopefully I now have a clean system to work with.
I will try updating it to debian again because I think there are advantages to it. I use a modified version of the 'custom sleep' program that worked with the Buffalo 'auto sleep' mode functionality - that program will need some modification I suspect.
In retrospect, and tbh, I think I missed a step from your 'post installations' instructions (I was using Novaspirit Tech's YouTube video as my prime source and he whizzed through the process) As a result, I trashed my md2 partition and my attempts to recover it were only making matters worse. I don't know RAID and should have been circumspect in my actions. But that's how I learn; leaping in, trashing stuff and recovering from it! Not recommended practice but it adds to the thrills
Edit: having successfully installed debian and got the nas up, restored and running, I set to modifying my 'custom sleep' programs. I quickly realised there was more work in that than I wanted - so I've reverted back to the stock firmware. In short, the programs need to be able to find the status of the auto switch and that was a feature of the stock firmware. I looked
phy_restart.sh (from the
device specific notes) but I was unable to work out if that'd tell me what I need to know and, if so, how.
It's been a fun exercise and has kept me amused in these 'lock down' times!