Missing Disk Space after Extending Partition in Windows Server 2008 R2

I was running out of space on the boot partition of a mailbox server, so I ordered a couple of new drives. Since the drives are in a mirrored array, it was simple to replace them. We simply pulled one old drive out and put a new one in, then waited for the mirror to rebuild. When that was done, we replaced the other old drive in the same way.

After replacing the two mirrored disks of the boot drive, we used the Disk Management Console to extend the partition.

That’s when the real trouble began.

The Disk Management Console showed the correct partition size, but Windows Explorer still showed C: drive with the old, smaller size. I started up DiskPart–which also showed the correct partition size–selected the Boot volume and ran “extend filesystem.” That returned this error:

DiskPart has encountered an error: The device does not recognize the command. See the System Event Log for more information.

DiskPart has encountered an error: The device does not recognize the command. See the System Event Log for more information.

There was nothing at all related to disks, volumes, or partitions in the system event log.

Thinking that perhaps we had extended the volume too far without leaving enough space for the file table, I attempted to shrink the partition using the Disk Management Console. That produced this error:

Virtual Disk Manager: The parameter is incorrect.

Virtual Disk Manager: The parameter is incorrect.

That’s not cool.

I scanned the disk for errors, but it came up clean. While I was looking at the disk tools, on a whim, I defragmented it, then went back to DiskPart and re-ran “extend filesystem”. Gold!

I don’t know why, but a defrag fixed it.

7 responses to “Missing Disk Space after Extending Partition in Windows Server 2008 R2”

  1. Marc says:

    I just had this same problem on a VM and this worked. Thanks!

  2. MarjmMmaM says:

    I had this problem, but defrag did not resolve. In my case, a backup app was access VSS. Stopping VSS resolved the issue.

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