I have an MPU which was Fat 32 format, it became stubborn to eject this drive on my mac desktop, ever since then ( last week) when plugged into my mid 2009 MacBookPro with El Capitan I get this error message in rotation. I tried running the WD drive check but it did not flag up any issues.
I since set the MacPro to use WD util to reformat the drive as a Mac drive but the error appears each time it is connected to the MBP. I have never used it as a RAID and use it as an external storage drive. I just bought a new 3TB My Passport and if it becomes as big a problem as this one I’l be regretting it soon