LS220DDA4 4TB Buffalo Unit (2x2TB)

[axraj]

LS220DDA4 4TB Buffalo Unit  (2x2TB).

1.  Configured as RAID1.
2.  Operating in degraded mode with amber flashes on the front of the unit.  Data seems to be all there on Array1.
3.  In the RAID section Array 2 shows "unformatted".  Is going forward with  "Recover RAID array" advisable?   selecting it takes you to the next step which is a question - All data on the disk(s) added to the array will be lost. Proceed?
4.  Will I loose data on Array1 if opting YES to proceed?  What is the Risk?

[Texturtle]

Recovering the RAID should not cause any data on the array to be lost. As always, we recommend a good backup of all data at all times, but recovering the array is a normal procedure. I would suggest that you look at the drives and determine which one has fallen out of the array. It may need to be replaced.

[axraj]

I concur with your perspective that RAID is not a substitute for a good backup. 

However, my acquisition of the Buffalo unit was to have a back up of my PCs with the added protection of the RAID mirror.  Now my mirror (Array2) seems to have malfunctioned and I need to restore it.  Array1, continues to perform in a degraded way and seems to have all my backed up data.  Do I now need to backup Array1, before continuing with attempting the "Recover RAID Array"? 

You are also correct with the potential that a disk may need to be replaced.  The manual indicates
For RAID 1
Navigate to Drives - RAID in Advanced Settings. Select the array with the error, then click Recover RAID Array. Follow the procedure on the screen to complete the hard drive replacement.

So, I cannot find any reference in the manual that I can continue with "Recover Raid Array",  not loose data on Array1 due to this action and that it is a routine recovery step.

Thank you so very kindly for your response.

[Texturtle]

The warning indicates that any data on the drive that is the target of the rebuild will be deleted. This is expected. For instance, in a two drive mirror I replace drive 2 and rebuild the RAID. Anything that existed on the newly installed drive will be overwritten during the rebuild. This procedure is NOT expected to remove data that is on the RAID array. Just make certain that if you replace a drive, it's the failed drive that gets replaced.