ReadyNAS 214 volume is inactive or dead.

There are several things that can cause this problem - some can be easily repaired, others cannot be.  It looks like your volume should be 4x2TB RAID-5 (that would have a ~5.44 TiB volume size) - but I am only seeing 3 disks in your screenshot.  Should there be 4 disks?

There is a lot more information in the full log zip, so begin by downloading that from the logs page. 

I can analyze the zip for you if you like.  Normally it is best to send the log zip via a private message (using the envelope icon in the top right of the forum page).  But they changed the forum software yesterday, and AFAICT that facility isn't working.  If you can figure it out, then send me a PM.  

Upload the log zip to cloud storage (dropbox, google drive, etc) and include a download link to the zip.  Make sure the permissions allow anyone with the link to download.   There is some privacy leakage when you post the link publicly (which is why I always recommend a PM).  I will reply when I get it, so you can remove the zip from cloud storage (minimizing the potential leakage).