Failed Redundancy Error on Windows Server 2008 Mirrored Volume

So I helped a friend set up a home network. He has a Windows Server 2008 server with multiple disk drives set up. These drives are mirrored. Somewhat frequently the Failed Redundancy error pops up. The first couple times we looked up how to fix this and fixed it without a problem. My question is why does this keep happening? It seems more frequently than I would've expected (maybe every month or two). Just wondering if we configured something wrong that may be causing it or if it is because the drives are low quality. If it is the drives themselves, is there some sort of spec on the drives we should look for? I've attached screenshot of disk mgmt.

Thanks for your help!

Screenshot

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