still got me beat even used 14.04 and 15.x live boot disks they would not even pick up my flexraid drives at all
yet any other drive I mounted after flexraid had been started worked
for now Ubuntu 16 has been randomly picking up drives mounted at boot ,
after 100+ reboots I only had 1x left to mount / swapout DRU4
but on reboot the ones that were swaped out where back to showing missing
what ever it is its something on the partitions preventing flexraid to detect these drives
I recovered the files I accidentally deleted with R-Studio ,
root@aio:~# fsck /dev/sde
fsck from util-linux 2.27.1
e2fsck 1.42.13 (17-May-2015)
ext2fs_open2: Bad magic number in super-block
fsck.ext2: Superblock invalid, trying backup blocks...
fsck.ext2: Bad magic number in super-block while trying to open /dev/sde
The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem. If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>
or
e2fsck -b 32768 <device>
root@aio:~# fsck /dev/sdh
fsck from util-linux 2.27.1
If you wish to check the consistency of a BTRFS filesystem or
repair a damaged filesystem, see btrfs(

subcommand 'check'.
still no idea why the partitions are running 2x types when they should all be ext4.. I might just have to start them again by scratch but would like to know why a perfectly working system stopped working after an OS update ...
I might try matching them up in the fstab as ext4 / btrfs and see what happens
*edit*
the only thing left is to see if FlexRAID-2.0-Final_u11b.bin works
as I know FlexRAID-2.0-Final_u12b.bin gave me problems last time
*edit*
now I can not get any old flexraid drive to show when mounted
I am at the stage I think my only solution is to blank out an PPU drive copy DRU content onto it rinse repeat and start again
I really do wish I knew what flexraid writes to the /Meta / MBR / GPT / Partition Tables to cause these issues ...
which would make this the third time I have had to start from scratch from an OS update