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I am trying to RAID 1, two hard drives in Windows Server 2008.

  • They are the exact same make and size.
  • One has data on it the other is blank and formatted.
  • They are both set as dynamic disks.

When I try to right click "Add Mirror" on either of the disks - the option is greyed out. Why?

PS - Is it possible anyway - to mirror an existing drive with data on it to a blank hard drive, or do you have to start from scratch and have two blank and formatted drives?

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up vote 3 down vote accepted

you should be able to add a mirror. try deleting the formatted partition on the empty drive.

This site steps through the process (which you probably already know), but it does not specifically say whether the second drive needs to be empty. the closest it gets is to say:

When a mirror is added to an existing volume Windows creates a second volume equal in size and file system type on a second disk of your choice and copies (a process also known as resynching) the data on the existing volume to the mirror.

However, this Microsoft KB article (which deals with Server 2003) does state that the second drive must be unallocated.

In this scenario, disk 1 is the disk on which the image of disk 0 will be mirrored.
1. Disk 1 must be unallocated space before you can proceed with mirroring.

Early this year i had to do the exact same thing on Windows 7. I know i managed to set-up the mirror without destroying the data, so it is possible. Alas, i do not recall exactly the steps i took.

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Is a formatted partition definitely a problem in this case - I only ask as it took about 10 hours to format and I don't want to have to do it again unless absolutely necessary. Cheers – Vidar Nov 9 '10 at 17:01
10 hours to format, use the quick format option, it only takes 20 seconds or so. – Moab Nov 9 '10 at 18:12
Little point in doing a full format - it's only doing a chkdsk for the vast majority of that time. And yes, the disk MUST be unallocated. – Multiverse IT Nov 9 '10 at 20:09
I deleted the formatted volume and hey presto I was allowed to add a mirror. Its working nicely now! – Vidar Nov 22 '10 at 13:32
glad to hear it – Xantec Nov 22 '10 at 15:10

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