well, my idea was to make that manually first with steps like:
- lfs mirror extend -N <new DOM layout> <some non-dom file>
- lfs resync
- lfs split --mirror-id 1 -d
and make it work, it is not working just out of box and requires code update to make DOM code understand FLR cases, e.g. DOM component can be not first one with FLR, but still should be first one inside a mirror, also we need to allow only one DOM component in all mirrors and so on.
I think that will be good as first step, at least simple script will be able to migrate files to MDT like that and Lustre code will be ready for FLR+DOM configurations. I'd say it shouldn't take a lot of time, but let me do more checks first.
Next step will be implementing that in code as single call, probably with some optimizations.
Landed for 2.12