Hi,
1) Disks are configured in RAID 1. On both now I see the same partition table
2) I tried to mount on Linux because files were not accessible via file manager, web interface, SMB mount etc. Normally I mounted volume using smb. Before the fault I tried to mount the volume but, unexpectly, the unit was unreacheable because was off. I booted the unit and I worked it normally. During normal operation unit stops to work. When I checked Volume from web interface both disks were offline, leds were amber and RAID seems not configured. At this stage all files were not accessible using NAS, so I decided to use an USB caddy and check one disk on my PC. Ubuntu was not able to mount automatically and filesystem was reported damaged, I tried also on Windows with same result.
3) Disks are Western Digital Green WD20EZRX 2TB
4) I accessed NAS in read/write till few minutes before the fault.
5) I used Gparted only to check the partition table becuyse both Linux and Windows reports the filesystem unaccesible. I was astonished to seen that filesystem was marked as swap area.
Some notes:
a) Gparted was used only to check the consistency of partition table, My first guess was that the whole partition table was damaged but I verified that all other partitions are normal
b) NAS is set for RAID autorecovery, So I suppose a bad recovery of a damaged disk, i.e. NAS was off for a power fault that generate also a fault of a disk, when unit comes up autorecovery started but it syncronized the wrong disk on the good one. Could be reasonable?
c) Is there any that I can check to verify it?