I have pretty much the exact
I have a TS-410 and had a mirroring RAID 1 with two 2TB drives (for a total available capacity of about 1.8TB). I wanted to add an additional two 2TB drives to the RAID 1 and migrate it to a RAID 5, but my RAID was listed as in degraded mode, so after unsuccessfully trying to fix it (along with problems logging into the NAS), I backed up all the files to an external drive, formatted my NAS drives, and reset the NAS.
After wiping the disks, I installed one drive into the NAS and set it up as single-disk. Then I copied all of my data back to the single-disk NAS. Once that finished, I installed the other three 2TB drives into the NAS and migrated the single-disk into a four-disk RAID 5 configuration (for a total available capacity of about 5.4TB). (I followed the migration tutorial at http://www.qnap.com/USEng/pro_features_RLM.asp
exactly as described.)
However, my Web Admin page lists my RAID 5 (with the full 5.4TB capacity) in addition to
the single-disk (with about 1.8TB capacity). Also, like the OP, all of my data is on the single-disk, not the RAID, so I have no data protection right now except for the external hard drive backup. Initializing the RAID 5 took about 40 hours, so I'm hoping I don't have to remove the RAID configuration and re-initialize it.
I'm going to contact QNAP Support about it, but if anyone else has any ideas or recommendations, I'd really appreciate it. Thanks.
Here are pics from my Web Admin: