Windows 2008 R2: can't extend C drive, mystery partitions

Question

I have a Windows 2008 R2 server running under VMware ESX 4.0.0. I have reallocated disk space to it in order to extend the C drive, but Disk Management has "Extend Volume" greyed out. DISKPART shows more partitions than Disk Management shows, including one after the volume I'm trying to extend, which would explain why Disk Management isn't allowing the extension.

Disk Management shows:

System Reserved / 100MB NTFS / Healthy (System)  
(C:) / 39.39 GB NTFS / Healthy (Boot, Page File, Crash Dump)  
10.00 GB / Unallocated  

DISKPART shows:

Partition 1    Dynamic Data       992 KB    31 KB  
Partition 2    Dynamic Data       100 MB  1024 KB  
Partition 3    Dynamic Data        39 GB   101 MB  
Partition 4    Dynamic Data      1024 KB    39 GB

My question at this point is: what the heck are partitions 1 and 4, where did they come from, why doesn't Disk Management show them, and, most importantly, can I delete partition 4 in order to extend partition 3?

Solution

A few hours later, "Extend Volume" became active. The tech that performed the extension didn't look at the partitions before he did it, but now with the extension complete, it shows the same mystery partitions, with #4 "magically" relocated to after the extended #3.

The only thing that any of us can think of that was done to the system was run a "Rescan Disks" from Disk Management. (The space extended into was created only a few hours earlier — I probably should have mentioned that — so this might be relevant.)

If and when this happens again, I'll try and remember to update here. If anyone can confirm or deny if they're in the same situation, that would also be helpful.

Comments

[Zoredache]

Under Vmware what? Have you considered running Vmware converter to make a new VM with additional storage? It would do the resizing for you.

[wfaulk]

Customer wants expansion done without (or at least with minimal) downtime, which makes VMware Converter non-optimal. [updated VMware version: ESX 4.0.0]

[wfaulk]

If that were the case, wouldn't they still be showing up in Disk Management?

[TomTom]

Not necessarily ;)

[the-wabbit]

A number of partition types is defined as "hidden" for various purposes. Not sure what the disk management MMC snapin would make out of it. Diskpart's list partition should show them all, though.

[Admin]

I can confirm. I was just in the same situation on a 2008 R2 server running under VMware ESX 5.5.0 . "Extend volume" was first greyed out, so I ran Rescan Disks and then it went active.