Are you seeing disk failures or an inactive volume status in the admin web ui?
Do you have a backup of the data?
You might want to use paid netgear support (via https://my.netgear.com ). Don't use the gearhead support. There is a per-incident option, if you see that I suggest using it.
Another option is to download the log zip file from the web UI and ask one of the mods ( @JohnCM_S or @Marc_V ) to analyze it. Send them a private message (PM) using the envelope icon in the upper right of the forum page. Upload the zip file to cloud storage (dropbox, google drive, etc) and include a download link in your PM.
