VM Disk Size

Copper Contributor

Hi Folks!


I'm curious if there is a way to increase the default disk size or add additional disks for Lab VMs? Some of our software packages are quite large!  I haven't seem mention of this in the documentation or in the UI. Does it have to be done via PowerShell/AzureCLI?


Thanks in Advance, 



13 Replies



I believe the feature is coming as we've asked for this too. But there's no ETA yet.

So for now you're stuck with the default 128GB.

best response confirmed by Patrick Wahlmüller (MVP)

@tdickieson - One thing that I want to point out is that there is a general paradigm shift when you switch from a physical lab to using Azure Lab Services.  A key difference is that Azure Lab Services is designed to spin up and tear down labs quickly as your needs change - typically, we recommend that you have 1 lab per class so that you only need to install the software for that one particular class and then when the class is over, you tear it down again.  This is different compared to a physical lab that is shared by multiple classes and that requires all classes' software be installed at the same time.  In most cases, if you create 1 lab per class, this typically reduces the amount of software that must be installed at one time within the lab and then reduces disk size needs.    However, there are sometimes exceptions that a particular piece of software requires a larger disk size - if you have this situation, let us know.

With our environment, we will run anywhere from a single client up to 4 servers and 4 clients on a host. The 32gb of ram will handle it, but the 128gb space will limit the use of snapshots for students to use while doing their lab work.

@AndrewStrahl - Sure, this info helps me to understand your scenario.   Although the current disk size is 128 GB, we did recently write a blog post that provides tips to help with nested virtualization.  Here's a link to this post:  In particular, refer to the guidance provided in bullet #2 in this post.




I think the default is to thin provision the disks (using vhdx).
For us it's not the size of the disk that is cuaing issues, just the ability to take multiple snapshots of each VM.
For example, if we have 6 VMs, and ten assignments for the class, they would need nine snapshots if they want to go back and practice.

@AndrewStrahl currently the only other options I can think of would be to store the snapshots externally from the VM.  Or, the other thought is to create multiple labs for the class so that the students use a different lab\VM depending on the set of assignments that they are working on.  I realize that neither of these are ideal, but may be ways to work around this in the short term.


We have received this feedback before that for nested virtualization, a larger disk size than 128 GB would be useful.  I'll make sure your feedback is tracked on our backlog to consider for the future.

We thought of attaching a storage share in the VNet for students to store snapshots. This is fairly new for us (just learned of lab services two weeks ago) so we are still figuring out what works and what won't.
We won't give up, I'm sure we can find something that will work.

Gotta admit though, this is such a game changer for us during covid!

@AndrewStrahl glad to hear that Az Labs is helping out.  If your school needs any assistance with setting up labs based on the various needs of your classes, please let us know.  We can potentially engage with your school\IT department directly to help implement this.  


Also, we really appreciate your feedback.  I would be interested to know what option you decide to go with to work around the 128 GB size limitation.  And, we're always interested to learn more about the types of classes\scenarios that schools are using Az Labs for.




@tdickieson I have the same problem, I am trying to build a Hyper-V lab of VMs on the large instances (8 cores, 32GB RAM, nested virt) but 128GB of space is extremely limiting. I could find solutions for most of my other problems (how to transfer ISO files efficiently with a network share inside the same virtual network, for instance) but the disk size is definitely going to be a difficult problem to work with. I wish I could just pay more for a larger disk.

Hi @nicolehaugen!
Thanks for the response. I do understand the paradigm shift, and I'm all for it! I guess for one we do run into these "edge case" exceptions with very large software packages. Especially as some of these applications require a substantial data set to ingest or export and there insufficent space on the disk. I understand there are work arounds for this, which we are leveraging (i.e. file shares, blob storage, etc.). It's just that it would certainly be much more efficient in some cases to just have a slightly larger disk or ability to attach a second disk.

In the higher education context, another situation we run into is when one professor, teaching one course, requires multiple applications for remote instruction. We end up having to create multiple VMs for each student (even though they are in one course) and make sure the students use the correct VM per application. When they need to feed the output from one application as input for another application, well, you see how this starts to get overly complicated.

Again, I appreciate the response. We are using various work arounds right now. I just thought it might be helpful to just leave some feedback on our particular use cases as I figured there may be others in the same situation. Having the option would certainly help sell this solution to more audiences in our space.
What could also help: compress the hard disk with NTFS compression.
I haven't tried this yet but since the VMs can be peered there's no reason they couldn't access a storage device in the same Vnet network.
I have never tried using some sort of network storage for Hyper-V virtual machines, but if you have good references (docs, blog posts, etc) I'm willing to take a look at it. However, this would only really be usable for read-only resources shared by all VMs: if everybody has a fully copy of the template VM, external shared storage doesn't duplicate itself. Each student gets a fully isolated copy of the template VM to play with, anything stored externally unfortunately breaks the isolation.