NASLite Network Attached Storage

My friend who also uses NL_M2-64 got this problem yesterday when trying to connect to one of the drives (Disk-2). He has 4 drives where Disk-0 mirrors to Disk-1 and Disk-2 mirrors to Disk-3, suddenly he can not connect to Disk-2, he could open the web page for NL and see the information but the SMART was not working so I went into admin to see if I could run the Check drives but got the error in the picture below. Same error for both drives (Disk-2 and Disk-3). I then restarted NL and drive 2 and 3 was lost. What can possible go wrong and is there an easy fix before I start to run a rescue mission. What I understand from him he has not done anything special and no turning off the NL, it has been running 24/7. Disk-2 mirrors to Disk-3 for backup I guess the error got mirrored over to Disk-3 as well and are now in the same condition as Disk-2. I have now taken Disk-3 out and will connect it and see if I can run some software to fix the drive or rescue the files. Why this suddenly error? This makes me worried if this can happen more times on other machines as I rely on NL for my backups.

Thanks

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Trying to figure out why this happened...

It mirrors the drives overnight, can it be an "hicup" in the power line like a surge who causes this? I have no other good explanation... as two drives went out on the same time.

I am now on a rescue mission and have tried 3 recovery softwares all have failed (seing only the free space left) except one.

R-Studio is the best so far but it takes ages to recover, over three days for making a image file before I will try to make a recovery.

I wish there could be some type of recovery tools in NL that could be able fix such corrupt files in admin mode, a future request