In reply to Amenhotep's message of 22 Jan 2026:

Doesn't that mean that it's just one disk really ?

Yes and no

MD raid on Linux should (should is important) read from two RAID1 devices in sequence as RAID0.

I've tweaked the database to do some more aggressive reading and caching and mostly not flush the data after every write -- the server is backed by 25kWh worth of LiFePo4 batteries running of solar so if the grid goes down there's still something like 15 hours of runtime "with no sun" :-) and it seems to have improved the transitioner by about x2 the speed.

Thanks good luck