What is this temporary storage attached to my Microsoft Azure VM?

I follow the Microsoft Azure article How to Attach a Data Disk to a Windows Virtual Machine and I am told not to use D:\ as a drive label because it already exists. Why is this?

Virtual machines created in Windows Azure are created with temporary storage assigned automatically.

Depending on the OS this can appear as:

  • Windows Virtual Machine “D:\”
  • Linux Virtual Machine “/dev/sdb1/”


Essentially, the temporary storage is used for the paging file of the running VM. Using local storage on the physical host helps to increase IOPS and lower latency when compared to standard Azure storage.

It is obviously possible to store data on this drive BUT  do not use it to store data that you are not willing to lose! The reason for this is, the temporary storage is created on the physical machine that is hosting your virtual machine. Should your virtual machine move to a different host due to hardware hardware failure or local host updating, the OS disk will be recreated from your storage account. However the temporary storage will be reallocated on the new physical host and any data will not be migrated from the original host. Other causes for the temporary storage to be recreated include when you resize your VM or when your VM is shutdown and restarted.

The size of the temporary storage changes between virtual machines but an up to date size can be found on this Microsoft Azure article Virtual Machine and Cloud Service Sizes for Azure

This image is from the Microsoft Azure Support Team Blog, but shows this process.


Powershell & Command Line

Deployment Image Servicing and Management: DISM

I have recently been involved with WDS and working on deployment images with DISM and found these articles to be of great help. If you’re planning to get involved in a similar venture these are well worth a read.

Powershell & Command Line

Edit BCD to allow dual boot of Windows 8

Using bcdedit.exe /enum

To enable the computer to also boot to a second Windows 8 you can use bcdedit.exe with the following command which will copy the current Windows Boot Loader details for Windows 8 to a second record for Windows 7/8 or Server 2012.

bcdedit.exe /copy {current} /d “Second Microsoft Windows 8″

bcdedit.exe will respond with something like the following.

The entry was successfully copied to {…………………………..}.

Using bcdedit.exe /enum to again enumerate through the current entries within the BCD store you’ll see the newly added entry.

Before you can use the newly created Windows boot loader configuration, you’ll need to change the partition for the second Windows 8 using the following two bcdedit.exe commands.

bcdedit.exe /set {……………………………} device partition=D:

bcdedit.exe /set {……………………………} osdevice partition=D:

If you now reboot the system you should now be able to boot into either copy of Windows 8.

bcdedit Information

Day ONE for

Welcome to the home of my technical blog.

Having worked in the IT world for many years, I felt it an appropriate time to setup my own technical blog. Somewhere to be able to post and share nuggets of technical information. Predominantly Microsoft solutions, I felt it a good way to document any helpful tips, not only for myself, but for anyone else that may find them useful.