Fastest Disk for Running Virtual Machines?

I read a discussion the other day about a laptop review as well as comments about running virtual machines on a Solid State Disk (SSD).

The two comments that made me think were (to paraphrase):

1) “I heard running virtual machines can cause issues with your SSD

2) “I don’t notice a large performance difference between running a virtual machine on an SSD and a normal disk

These comments were of interest to me since I run my primary virtual machines off my SSD disk. Am I potentially trashing it for no performance improvement?

I put together my own speed test based on a few disks I have lying around.

The contenders are:

Disk  Connection Comment
Intel X-25M SSD (160GB)  SATA My Solid State Disk in a laptop caddy
Western Digital 7,200 RPM 2.5” (200 GB)  E-SATA Generic external enclosure
Western Digital Passport (1TB)  USB 3 My latest external disk
Western Digital Passport (80GB)  USB 2 My first external disk, still going strong after 6 years
(From Left to Right) Intel X25-M SSD, Generic WD e-Sata, WD Passport USB3, WD Passport USB2


This test is definitely not exhaustive, and applies only to Hyper-V and my particular laptop configuration.

In addition, only some general aspects of the newly released Windows 8 (Developer Preview). The comparisons for the operations that interest you may be quite different. The comparisons I made were just to determine if there was a trend between the underlying disks.

A better test would do similar comparisons between Virtual Box, VMWare, Virtual PC etc.

Finally, the SSD had the advantage of being directly connected to the main SATA bus. I could have tested a normal disk in the caddy as well, but I felt e-SATA should be nearly as fast (if not as fast).

Test Setup

I have created a 20GB Hyper-V disk file with Windows 8 installed. The same file is copied to each of the disks above.

The Hyper-V machine for each has 4 processors with 4092MB of RAM. The configurations are identical.

Just to make things fair, I tested each machine twice by shutting down and then starting again.

The laptop was a Lenovo W520 with an i7 CPU and 16GB of RAM. The operating system was Windows Server 2008 R2 Standard Edition.

Nothing was running except for the Hyper-V process itself, and only the machine being tested run running.

A list of my Hyper-V machines. Windows 8 test machines at the bottom


I just tested and timed some simple operations in Windows 8 that anyone can do out of the box.


The results in seconds are below:

Test  Intel X-25-M WD e-Sata WD Passport USB3 WD Passport USB2
Windows Startup 





Windows Login 





Launch Visual Studio 11 





Build basic HTML5 solution in Visual Studio 





Launch Expression Blend 5 






There is a considerable speed advantage to using a Solid State Disk for running your Hyper-V virtual machines.

e-Sata still proved to be slightly faster than USB 3.

Surprisingly, USB 2 was not extremely slow compared to its USB 3 successor.

What Next?

I recognize that by using my SSD to run virtual machines, I am potentially reducing the life of the disk quite considerably.

At the time of writing an Intel SSD with 160GB is retailing at USD $300. Therefore the productivity advantage (for me) seems to outweigh the cost of the disk itself.

I will still run some machines (such as Active Directory and betas) on a ‘normal’ disk.

I’m also likely to use USB 3 more from now on. Although my e-Sata disks are a little faster, I find the connection more temperamental as well as needing two cables (data + power) which is inconvenient.

5 thoughts on “Fastest Disk for Running Virtual Machines?

  1. Hello Andrew,

    Thank you very much indeed. A very well written article that was has helped me immensely, given that I have almost exactly the same situation and dilemma.

    I have an i5 laptop with 8Gb of RAM, and have just ordered an OCZ Vertex 3 internal SSD drive to replace the existing HDD. I also have an external WD Passport USB drive.

    As part of a search project I will be needing to create an run a number of VMs (using VMWare Workstation) that will be used in groups of three in a lab to test out how different peices of software work together with different flavours of Windows and Exchange.

    Given that I don’t have masses of RAM to play with I too asked the question about there being any advantage in terms of performance to use the external drive over the internal SSD drive.

    So apart from the question of degradation of the SSD drive over time, it would seem based on your benchmarks that using the internal SSD drive gives the best performance by some measure.

    I would also agree that the productivity advantage for me also seems to outweigh the cost of the disk itself.

    Thanks again for writing this excellent article.

    Kind regards,

    James Gillies

    1. Hi James, thanks for the feedback!

      In terms of running three virtual machines at once, I think you would get better performance out of more RAM and a normall HDD, than 8GB and an SSD. I’m guessing however that isn’t an option for your laptop?

      (For reference I run my Win 2K8R2 Active Directory with only 512MB RAM, which helps the other machines out)

    1. Sure, it is an interesting area and I thought that I would be doing more tests. Main issue right now is that I see most of my work being in the cloud and my days of spinning virtual machines locally may be numbered.

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