OK, time to close this threadAfter a generous assistance, the IDRAC logs have been reviewed and both controller and drives are fine.The culprit was a USB drive that I assume was going bad, and Window3s server was misreporting the errors as coming from the raid array.Removing the bad drive stopped the error logging and AOMEI Backupper is now starting and not hanging.I hope that this will save time for someone in the future.David L.  
PowerEdge T420, Perc H710, all drives show healthy, so does the raid controller in iDrac Windows server 2012, standardThe error started showing a few days ago, the server is still running, only one program AOMEI Bacupper hangs on startThe: Reset to device, \Device\RaidPort4, was issued. keeps being logged as well as: The IO operation at logical block address 0x0 for Disk 4 was retried.Is the H710 starting to fail? Is this a windows device driver issue? What are my option before I call Dell for support?David L.
Reset to device, \Device\RaidPort4