'Add mirror' greyed out in Windows 10

Question

Added a 5Tb drive and trying to mirror my data drive (1.5Tb). When I add the drive, it shows 2 partitions , one is 2048gb, the other 2609gb. I wish it was 1 fully unallocated partition and am not sure why they're split but they're both unallocated. I converted my data drive to a dynamic disk so i could 'Add mirror' to one of the new partitions but it's greyed out. Why is it greyed out?

Running windows 10 pro.

Answer 1

The reason it's grayed out is most likely due to it not being part of your storage pool. To set up the storage pool, hop in to control panel and select 'storage spaces'. Set up your alternate drive into your pool, and you'll be set. Here are some resources to help you on your way:

http://www.windowscentral.com/how-use-storage-spaces-windows-10

http://www.howtogeek.com/109380/how-to-use-windows-8s-storage-spaces-to-mirror-combine-drives/ (specifically for win8, but still relevant)

Answer 2

My mirror option was grey until I unalocated volume and had left disk free.

Answer 3

To make any drive bigger than 2tb appear as one space, it needs to be converted to a GPT disk in windows Disk Management.

It is possible to add a mirror without using windows Storage Spaces or losing data on the source disk. In windows Disk Management, ensure your destination disk is an empty, unallocated basic drive of equal or greater size than your source disk. Right click on your source disk, and 'add mirror' should be there, not greyed out.

It was greyed out for me when I first tried because I had formatted the destination drive - the key is for the destination to be unallocated. Do this by right clicking the destination drive and choosing 'delete volume'.

I'm on Windows 10 Pro 1903.

Answer 4

For the people running Home edition, you'll need to upgrade to Pro or Enterprise: Software RAID Windows 10

Answer 5

I read the accepted answer and feared that Windows 10 was now suddenly going to force me to clear my drive and setup a "Storage Space" before mirroring it, even though this was not the case in Windows 7. Turns out, this is not the case at all.

I was having the same issue. Here are the steps I took to fix it:

1. Installed new HDD and opened Computer Management to see my healthy data drive along with the new drive, which I initialized as GPT. When I right-clicked the data drive, "Add Mirror" was grayed out.
2. Tried converting both the new drive and the existing data drive to Dynamic. No change.
3. Tried formatting the new drive. No change. Decided to delete the new partition and leave the empty drive un-partitioned for the time being.
4. With the now un-partitioned new drive and the still healthy existing data drive, both set as Dynamic, I was still getting a grayed-out "Add Mirror." I checked the properties, and sure enough, I had initialized the new drive to GPT but the existing drive was actually initialized as MBR. I tried converting the empty drive to MBR.

At this point, when I right-clicked the existing data drive, "Add Mirror" was no longer grayed out. I was able to mirror the existing drive with all data in tact to the new empty drive.

So to recap: both drives Dynamic, both drives MBR, left the empty drive un-partitioned, and "Add Mirror" worked perfectly. I am using Windows 10 Enterprise.

Answer 6

I know that this is an old question, but to answer one part of the question about the 5TB (for anyone who finds this page through G), MBR allows partitions of up to 2 TB (2048 GB). Converting the disk to GPT allows partitions much larger - up to approximately 9.4 ZB.

Ref: https://en.wikipedia.org/wiki/GUID_Partition_Table#History

Answer 7

It's important that the disk you are trying to add (which should be same size or bigger than the source disk) has no volume. So you need to 'delete volume. Once Disk Management finds a sufficiently big unassigned disk, the 'Mirror' option on the source disk will no longer be greyed out.