My Book 6TB appears unallocated under Windows 7

It had been connected partitioned as 2 disks to a Vista PC for a while and worked fine. It was set up as RAID 1, so the 6Tb appeared as one 3Tb. One partition was 2TB and the second is 1Tb. It worked fine.

I got rid of the Vista PC and attached it to a new Windows 7 PC a year ago. Now Disk Management lists it as not having any drive letter, Healthy (EFI System Partition), and it is not initialized. The space is unallocated. I cannot get the two drive letters to appear. It has never appeared when connected to the Win 7 PC; I just got around to troubleshooting it now.

It is connected to USB in the back of the PC.


Make sure the drive is plugged in directly into a wall outlet in order to discard any power issues. Also if possible try on another computer. If the issue remains then it means the partition could be corrupted and you will have to format it in order to use it again. If you need the data on the drive then I recommend you try a data recovery software or contact a data recovery company.

It is a RAID 1 array. Wouldn’t it fix itself? Power is definitely not the issue. I have the whole thing backed up with CrashPlan so I won’t have lost any data. I think I’ll just initialize it.

It was set up as RAID 1. Will that remain? The 2 3TB discs are set up as RAID 1 for a total usable of almost 2.8TB