For several years we have been speeding up the throughput on our VPC driven in-house Microsoft classes by placing the undo file on a separate physical hard drive from the hard drive that the virtual hard drive (vhd) resides upon. This gives a simultaneous write to the undo files while reading the vhd file. We’ve seen the biggest improvement during memory intensive situations such as the Just In Time (JIT) activation of .Net applications and the loading of services, such as during machine startup. If anybody has gone through loading SharePoint or loading the Cassini web server along with an ASP.Net web application on a virtual machine , you can attest to how slow it can be. We’ve seen increases in throughput of more than twice for these types of operationswhen comparing the separate physical drive approach to a single drive approach.
I’m currently working on a Metro training project for Microsoft teaching AX 2009 to ISV partners. The vpc for this class is almost 20 gigs in size and has AD, AX 2009, SQL and Office SharePoint all running simultaneously in one VPC. In an attempt to speed up the classes we had come up with a plan of me traveling the globe with 20 USB drives with the VHD files on them. The thought of me carrying on the airplane 20 2.5 inch USB hard drives just didn’t appeal to me. Enter the USB Flash drive approach. I tested a Patriot 32 gb USB Flash by placing the VHD on it and the Virtual Machine Configuration file (VMC) on the C : drive pointing to the VHD on the USB Flash. The undo file will then by default go on the same drive as the VMC file. Launching the vpc and operations like loading the AX 2009 interface, which by design also JITs Office SharePoint, where well over twice as fast under the single drive approach.
The write speed of the USB Flash is terrible; however, the read speed is around 10 mbs (faster than most 2.5 drives). In this scenario read speed was all we were concerned with since all writes took place on the local C: drive. There was also the added bonus that no classroom setup was required. All that was needed was a machine as it is normally delivered from the factory. I then signed out the USB drives to the students, they inserted them and setup the vmc file on the local hard drive, if needed VPC 2007 was also on the USB Flash.
We just finished this class at the Dallas and Reston MS offices and these were the first AX 2009 deliveries that had no complaints about VPC throughput, even though lesser or comparable hardware was used than in the previous deliveries. The only complaint from the students was that MS didn’t let them take the USB Flash drives with them and I have to agree with them on this point.
Give this approach a try and even though you probably aren’t working in as extreme a VPC environment that I tested in, you will see an increase in throughput. Not to mention the ease and practicality of working with your VPC files. Below is a picture of my 18 person VPC classroom fitting in the palm of my hand.