Experimenting with a RAMdisk
One of the slow operations in the MDT Deployment Workbench is the initial “Update deployment share” process that has to completely generate new Lite Touch boot images. I always assumed that this was slow due to the amount of I/O being generated by the update process.
Recently, ATI and Dataram released a trial version of their RAMdisk software at http://www.radeonramdisk.com (not that I am endorsing the product – it just happened to come through my Twitter feed and it works on Windows 8), so I had a chance to test the assumption: What would happen if the temporary storage used by MDT to generate the boot images would be on a RAMdisk?
So I installed the software on my laptop, created a 2GB RAMdisk, and formatted it as an NTFS disk. First, I “completely regenerated” the MDT boot images without using the RAMdisk. That process finished in six minutes and 15 seconds (6:15). Then, to get it to use the RAMdisk, I did the following:
- Start an elevated command prompt.
- Set TMP and TEMP to point to the RAMdisk (E:\ in my case).
- Run “mmc.exe DeploymentWorkbench.msc” from the elevated command prompt, so it inherits the TMP and TEMP environment variable settings.
- “Completely regenerate” the MDT boot images again.
That looks sort of like this:
So what difference did it make? Well, instead of 6:15, the whole process finished in 4:55. Not too shabby, about 20% faster, but I expected more. So why wasn’t it any faster? Well, it turns out it’s just a case of shifting the bottleneck. Watching the process using ProcMon and the Windows 8 task manager, I could see that the process was CPU-bound; the RAMdisk utilization was negligible. Hmm, I guess it’s time for a faster CPU…
The trial software doesn’t support server OSes or more than 4GB of RAM; you have to purchase the full version for that. Maybe I’ll try that sometime: Imagine a VM where the entire VHD is in a RAMdisk. I wonder how long that would take…