UPDATE (09SEP2013): There's a faster way. See: https://github.com/maartenba/WindowsAzureDiskResizer
I got into a bit of a predicament where the C drive of the VM I created here started to fill up. I needed to install some software that only gave me the option to install to the C drive. The installer was telling me there wasn’t enough disk space. Here’s what I did to increase the size of the OS disk of my Azure VM:
Delete the VM
Download the .vhd
Cloud Storage Studio is my favorite storage tool for Windows Azure. If you’d prefer a free option, then my next favorite is Azure Storage Explorer. Use one of these to download the .vhd file. This part is going to require a local hard drive with lots of disk space. You will need at least 2x the size of the original VHD + the size you want to grow it by. A fast internet connection will be a big advantage here as well.
Resize the downloaded .vhd
You can use Hyper-V Manager to resize your .vhd file:
My challenge was that the PC with the disk space necessary to store the downloaded and expanded .vhd wasn’t Hyper-V capable. Therefore, I used a tool called VHD Resizer from here. There is a nice walkthrough of how to use it here.
Delete the original .vhd from blob storage
Upload the resized .vhd
You need to upload the resized .vhd back to blob storage. I figured out how to upload it correctly after reviewing Step 5 from the Creating and Uploading a Virtual Hard Disk that Contains the Windows Server Operating System instructions. However, the command line switches for csupload.exe need to look like this:
csupload Add-Disk –Destination “<full blob url you want for your vhd>” –Label “<whatever you want>” –LiteralPath “<path to resized .vhd>” –OS Windows
Recreate the VM
I created a new VM via the management portal and pointed it to the .vhd file I uploaded with csupload. In my case, I had to re-attach an additional .vhd drive since my original .vhd was configured with an F drive where my database files were stored. Once your VM boots up, log in using Remote Desktop. For me, all of my SQL Server 2012 databases were in a recovering state. Not sure why. After I rebooted my server, everything was fine.
Use diskpart to get access to the unallocated part of C
Your C drive will still report the old size in Windows Explorer. You need to claim the additional unallocated space in the expanded drive. To do this, open a command prompt and execute the following series of commands in italics:
Make sure you select the os disk. For me, it was disk 0:
Find the partition that needs extending:
Select the partition. For me, it was partition 1:
Finally, extend the partition:
Now, you have the additional space in the drive you need to install more stuff .