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I have three disks. Disk0 (boot), Disk1 and Disk2. Disk 1 and 2 are both unformatted and unallocated drives. I am trying to mirror Disk0 to Disk1. They are both Dynamic and are both the same size (1TB). When I select Disk1 to be the mirror I get the error "There is not enough space available on the disk(s) to complete this operation". I have spent several hours searching for a solution but have not found one. Why do I get this error when they are both the same size?

EDIT: Shrinking the volume size on the boot disk by 100MB allowed me to get past this error. From what I read the mirror drive needs to be the same size or larger than the boot drive. So I am confused why that change worked. However, I now get the error " all disks holding extents for a given volume must have the same sector size and the sector size must be valid". I believe this is because the drives are different and one has 512B and the other is the Advanced Drive that is 4KB. What the different sector sizes cause both problems? If I got the same disks would both issues go away?

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I don't understand the down votes... this is a legitimate issue that I cannot find a solution for. Instead of just down voting could you also provide a comment that can help make this question better. Thanks! –  northpole Feb 8 '12 at 16:58

3 Answers 3

up vote 1 down vote accepted

A RAID1 array can only be as big as the smallest disk. Make sure that the volume you wish to mirror is the size you want it to be, then create volumes on the other physical disks that MATCH the size of the smallest disk. After all volumes are the same capacity, you should be able to create this array without issue.

This article here should help clear up some of the procedural steps:

http://www.techotopia.com/index.php/Creating_and_Managing_Windows_Server_2008_Mirrored_(RAID_1)_Volumes#Creating_a_Mirrored_.28RAID_1.29_Set_using_Disk_Management

Let me know if I can do anything else to help!

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Thanks for the response! Right, so the two disks I am using are identical in size (1TB) but have different sized sectors. The boot disk has one volume which is the full size of the disk. Disk1 (the mirror) is completely unallocated. When I shrunk the size of the boot partition 100MBs I got passed the original error. Now I get the sector size mismatch error. –  northpole Feb 8 '12 at 17:42
    
These two drives, are they identical in terms of Manufacturer, Make, Model, Size? –  JohnThePro Feb 8 '12 at 17:45
    
The drives are the same size but different Manufacturers (so different make model as well). –  northpole Feb 8 '12 at 20:07
    
If you don't mind, can you provide me that information? As a rule of thumb, when building RAID arrays, you want to have identical drives, and even better identical drives from the manufacturing run. –  JohnThePro Feb 9 '12 at 18:34
    
johnThePro - This was it, it was the fact that the drives were not identical. Once they were the same it worked. –  northpole Oct 9 '12 at 22:07

Odds are the disks will need to have the same number of sectors for this to work. I believe that when Windows does the mirroring it does a sector by sector copy so as you have less sectors on the new drive it can't copy everything. As to the size issue, everything needs to be the same to the number of bytes. I'm guessing that the new disk with the 4k clusters is a few bytes different in size. Using a disk with 512 byte sectors that is the same size as the current drive should do the trick.

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I had the same problem and managed to find a fix. I'll explain my steps and then give my interpretation of what happened.

assuming you have 2 disks, similar in size (diskA and diskB) also assuming you are already in Computer management (right click on My Computer and click manage)

In disk managment 1) create a simple volume for diskA. 2) right click on the volume you created and click Add Mirror (select diskB for the mirror) 3) This is where i got an error, however, it managed to successfully turn diskA into a dynamic volume. (yellow-green bar above diskA) 4) Create a simple volume for diskB 5) right click on diskB and convert to Dynamic volume 6) delete both diskA and diskB volumes 7) right click on diskA and create Mirrored volume.

My interpretation is that there is a flag on the volumes allowing them to becoming dynamic. Something in creating a mirrored volume from scratch and turning them into a dynamic disk was failing. Setting the flag for both volumes to be dynamic and then creating a raid drive worked.

Hope this helps

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It ended up being a problem with the fact they were different types of drives. They needed to be exactly the same in all respects. –  northpole Oct 9 '12 at 22:08

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