RAID1 from old release -> release 8.2

[siroB]

RAID1 two Seagate 7200.11 500Gb worked from 2009 to 2012 with old release of freeNAS (it is installed in 2009 and it was not updated)
when I saw problems with one disk, I shutdown system and install new release 8.2
I connect only a good disk and make "Import Volume", but disk contain only 12% of data and one directory
I connect only a bad disk and make "Auto Import Volume", disk contain all my data
I thought that on both disks there will be identical data...

Why on disks different data, after all they were in the RAID1?

 

[siroB]

Request failed (error=5)

I can't copy all data from disks...
"Auto Import Volume" and "Import Volume" any more don't work...
how I can restore data?
Thank you!