Lost all my data on my RN104 - anything I can do?

It is TWO disks failing not one. We would have sent email alerts about this if they were enabled at the time.

Also the status log shown in the web admin interface clearly shows warnings about both disks from last year (even though you wouldn't see the very old entries there now you would have seen them back then). Here are just a few examples of the many warnings given:

[14/12/12 02:54:18 MST] notice:disk:LOGMSG_SMART_ATA_ERR_30DAYS_WARN Detected increasing ATA error count: [10097] on disk 3 (Internal) [Hitachi HDS721010CLA332, ] 4 times in the past 30 days. This condition often indicates an impending failure. Please be prepared to replace this disk to maintain data redundancy.
[14/12/13 05:08:23 MST] notice:disk:LOGMSG_SMART_ATA_ERR_30DAYS_WARN Detected increasing ATA error count: [837] on disk 2 (Internal) [ST31000528AS, ] 3 times in the past 30 days. This condition often indicates an impending failure. Please be prepared to replace this disk to maintain data redundancy.

These entries correspond to what is shown in the smart history table (this table has always been there in OS6 but the smart_history.log that presents it nicely in the logs you can download was added in 6.2, I think). You would have seen an alert about these messages when opening the web admin interface if it was opened around that time.

Those ATA error counts are huge. A count above 50 would suggest replacement is needed. Some would replace with a non-zero count.

The disk showing green just indicates it hasn't failed completely.

Again if at all in doubt about messages like the examples I gave above it is better to ask.