@Dominma
Hello Dominma,
as being Technical Manager of a data recovery company, I can tell you that the sequence you describe, suggest that you have made the same errors that either experienced systems/network administrators do
:
1) you have not run a brief S.M.A.R.T. diagnose on the single drives. This mean
-- shut down an PC workstation
-- download crystaldiskinfo (also portable from
http://www.portableapps.com) and install it on the above PC
-- plug one and lonely of the NAS drives
-- check it with crystaldiskinfo. If the big rectangular icon it is not cyan colored and instead it is yellow or red, check which drive icon is of the same color (don't ask details, use the program, it is with a sharp graphic)
-- if the NAS drive is yellow or red, it must be cloned with proper devices like Atola or PC-3000 (unless you don't care at all about the data contained in the RAID)
-- repeat the check for every drive of the NAS
2) I'm pretty sure about the result you'll get from the previous steps.
The process is endless because you have some drive/s with so many bad sectors or even deeper SMART errors and you realistically are killing them with so many attempts without having done a copy of the single drives (cloning process)
-- NOTE CAREFULLY: cloning drives has two goals. Create a backup of the single drives AND make the recovery process fast. Since the cloned drives and or the bin images will be faster than those original damaged/wear drives.
-- NOTE CAREFULLY: everybody should avoid cloning with common PC and software those drives having bad SMART. During the process, the drive will hang on every bad sector for a long time (1 minute, 1 minute and a half) and they are pretty common the drives that in the end, have a bad sectors count like some 10.000 bad sectors. Try to calculate how many days are 10.000 minutes... During such long time (endless time), the drive will get damaged even more.
In the company I work for, we NEVER use the original drives for any kind of process: those drives are the UNIQUE copy of the customer's data. And you can be sure that every professional won't work with the original drives, too much risky, it would be like a Russian roulette.
Now you have enough info. It is time to give your data a value and think about to evaluate if they justify a do-it-yourself or not. If they are precious and or valuable, think about asking support to some data recovery professionals. If you need any info, fell free to inquire me with a
private message on this forum.
Kind regards
Cor