I built myself a NAS\SAN in my test lab using Windows Server 2012 Storage Spaces, a WD Black 1.5TB disk and a WD Green 2TB disk, Initially this worked well. With the success I decided to upgraded the physical disks to WD Red 3TB disks the process of adding the WD Red disks appeared to go smoothly and I was able to see the new storage from my virtual hosts.
A couple of days later I was preping to migrate the data from my WD Black to the new WD Reds before doing so I rebooted the server. Upon reboot within Server Manger – File and Storage Services – Storage Pools I noticed a yellow warning triangle next to my virtual disks.
My virtual disks had become detached and would not reattach as I was told the disk and name were already in use in the system.
After spending some time attempting to re-add the disks I tried some of the Powershell commands to diagnose the problem.
Get-VirtualDisk
Upon running the Get-VirtualDisk command I noticed that the ISManualAttach values were set to TRUE which did not sound right.
Upon searching for the Set-VirtualDisk parameters (http://technet.microsoft.com/en-us/library/hh848712.aspx) I was able to change this setting by using the following command in PowerShell.
Set-VirtualDisk -FriendlyName yourdiskname -IsManualAttach $False
I checked the settings had changed by running another Get-VirtualDisk and they had.
Upon rebooting and checking in Storage Pools my disks were attached and all my volumes and iSCSI disks were restored.
ITKnowledgeBase 
Useful tip. Had the same problem – VHD’s I used on Storage Spaces were not being attached / mounted on boot… which was a problem as the VHD’s were used to hold my VM’s in Hyper-V! 🙂
Thanks!
Hi,
great info! Saved my day 🙂
After new installation of Windows Server 2012 R2 (was 2012), the drive was not available and as I saw, detached. I assumed that it would be enough to attach and upgrade to the new Storage Pool version. But this was not the case because of the above IsManualAttach = $True.
Thanks!
Carsten
Thanks Martyn,
this was very useful as one such disk holding VMs (as Steve described above) starting misbehaving after an R2 update. Very weird, tell you, never got to understand why this happens since the disk status shows healthy.
Best!
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