if your raid is active then mount it somewhere and try to read data.
What type of FS is there on md127?
It is btrfs.
Ok, the funny part about RAID-1 is: if one disk fails in theory you have all your data still available since RAID-1 implements a mirror. You can throw one disk away and still work with the other since they should contain an identical set of data. Of course this does not work as expected since mdraid only tries to mirror data but takes not care of actually mirroring the data (it simply doesn't care about data at all)
RAID-1 was ok-ish twenty years ago when we had no better options. Today it's just insane to rely on something that inefficient and obviously not working. If wasting another disk for redundancy then please think about better ways to do this. And still you need backup since RAID NEVER provides data protection.
So why still relying on RAID-1 (reassemble the array with a 2nd disk) and not using the new disk to copy data over from the remaining RAID-1 member and now starting to implement a better strategy also taking care about data protection (with 2 disks you could use rsnapshot between those for example)
I will work on it, I need money for RAID 5 or 10 but I will work on it.
I have backups but not for any datas (ISO's, phone ringtones, wallpapers, drivers, game ROMS and very old video games).
I will lose wallpapers and maybe, very old video games only.
The others datas have a backup.