@derobert ZFS is amazing. So simple on the surface (really, very slick), yet so complex under the hood. It reminds me, in some way, git -- though taking a snapshot of a dataset in ZFS (read the analogous of a partition I think) is so simple. I will be switching soon into ZFS for all of my OS/Apps/Data partitions. Only one thing is missing for me: TRIM for the SSD.
@derobert I appreciate it that you (actually) reminded me for a Full Back Up. I did have a partial backup. And, it is true that back in December 2012, I have learned my lesson the hard way -- broken laptop hdd! It was very expensive :-/.
@derobert I don't have any more time to invest this. And, as I "found" ZFS, a perfect match (and even better!?) for what I was looking for, dropped the question. All in all, I think that some leftover command was assembling one array with the first disk (md127), then another with... another mdadm --assemble instruction (the md126). Dunno... Apologies & a Big TY for your efforts.
I hope I know now what I am doing. Onfe finished, I am all open on restructuring my Question, giving an Answer to all questions or close it if it needs be.
I am backing up everything, and give up. I think the best thing to do is to "so much nicer when there's decent backups, no need to fix things, just write over an oops." (from <http://www.linuxquestions.org/questions/linux-server-73/mdadm-raid-inactive-assemble-fails-with-device-or-resource-busy-4175422782/#post4760759>)
