You can have some of my hair, it's already gone......
What version of OS are you using???
All indications are a drive acting up. Verify the cooling fan is continuing running. The drives get real hot during a raid build.
Also post "co de info". This will give my drive info. For OS click on the SnapAppliance Logo on the admin page. A popup will give the info.
And was this unit every upgraded?
If you have a copy of SpinRite, run it under Maintance mode. New drives are not checked for bad media, this can throw off timing.