Since I don't like leaving unanswered posts, the answer is my Dell PowerEdge T110 II server was also logging Event 129 "Reset to device, \Device\RaidPort0, was issued" and Event 153 "The IO operation at logical block address 0x0 for Disk 2 (PDO name: \Device\00000043) was retried." to both drives in the storage pool at boot time.  Apparently this then causes the drives to go offline.  Despite a re-access correctly reads the drives. On moving one drive from SATA channels 2 to 1 (the second drive being on 3) one of the drives no longer logs this at boot and so Windows can initialize the storage pool as it can read the meta data from the drive.  Both drives appear Healthy after the boot completes. No idea why this server logs these events because the drives/server otherwise appear fine.  No Intel RST drivers exist so there's no software way of impacting these errors. I'm assuming it's a hardware or BIOS bug using 6TB drives on this server, but there is a workaround.  Of course if the channel 1 drive goes offline through failure there is a chance the storage pool would not initialize given that the channel 3 drive still gets that single IO error at boot.  But a "Rescan Storage" would bring it back online.
Hi I have a brand new T110 II and added two HGST Deskstar NAS drives (6TB) to the 1TB SATA boot drive and loaded 2012R2.  Boot drive runs fine. The two HGST drives are in the BIOS (Auto) detected and Windows can see them fine.  If I create a Storage Pool and add the drives, all is well.  I create the pool, a mirrored virtual disk and then place a volume on it.  All works great. I then reboot the server and the Storage Pool vanishes and drives show corrupt metadata.  I can reset the drives and recreate a pool and the same thing happens every reboot. HGST drive tool checks out both drives and they test ok, so I'm thinking that hardware wise things must be ok.  So either Windows Storage Spaces is broken for 6TB drives, or there is some other incompatibility with these HGST drives. Has anyone used 6TB SATA drives in a T110 II and know of any issues? Thanks
T110 II - Windows 2012R2 Storage Pool corrupts every reboot