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Experimenting with a RAMdisk

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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 https://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:

image

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…

Comments

  • Anonymous
    January 01, 2003
    I did that already with another RAMDisk, see blogs.technet.com/.../more-experimenting-with-ramdisks-using-a-vm-completely-in-ram.aspx.

  • Anonymous
    January 01, 2003
    Not really, as the CPU bottlenecks appear to be in two areas:  mounting the Windows PE WIM file, and servicing that WIM file using DISM.EXE.  So the improvements would need to come from those operations. There are some improvements to those operations already in the ADK versions of the tools.  I can see that both of my laptop's CPUs are being utilized by the operations (although the second one doesn't quite get to 100%).

  • Anonymous
    October 14, 2012
    The comment has been removed

  • Anonymous
    October 15, 2012
    Is it feasible to modify the source for "update-MDTDeploymentShare" to take advantage of multi-thread CPUs or the GPU (CUDA)??

  • Anonymous
    November 20, 2012
    "Imagine a VM where the entire VHD is in a RAMdisk"  .  You may try the Qsoft Ramdisk for this , see qsoftramdisk.orgfree.com/.../vhd.jpg

  • Anonymous
    January 05, 2016
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