1 Drive gone down

this morning got an email from my drive mirror that one of my drives have gone down, i have been able to login and can see one drive down.

why cant i see the files on its mirror ? no shares, no users?

URGENT

need to backup photos before loss to another drive

need to know right drive to buy, have sent support email, but its week end

ok panic over, i had installed a new NAS and had moved all my photos to it, so only movies on this drive. Anybody know which drive to buy to replace the bad one?

right now its showing 1 drive ok, other not at all, dont know why i cant see files from good drive? does it really need the second drive working to see files?

thought i would connect good drive to PC, but would need a program to see files?

Firmware Version : 2.11.178

WDBZVM0080JWT

My drive mirror (4TB) x 2
Raid 1

Ok ive bought 2 more WD Red Nas Drives, be here in few days

right now 1 drive fitted, can access files ok

1, fit new drive
2, wait re build
3, remove working old drive
4, fit new second drive
5, let it re build

So hope this is going to work, did try transfering filefrom one NAS to other new NAS takes very long time

wonder how long re build will take