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

Disclaimer

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

Testing

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

Results

The results in seconds are below:

Test	Intel X-25-M	WD e-Sata	WD Passport USB3	WD Passport USB2
Windows Startup	10	21	26	35
Windows Login	5	4	5	8
Launch Visual Studio 11	6	24	26	36
Build basic HTML5 solution in Visual Studio	1	4	4	7
Launch Expression Blend 5	2	8	15	19

Conclusion

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.

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