In MDT 2010 (and earlier versions), we provided some task sequence templates to perform what we called an “OEM preload” scenario, where you could send a disk image to an OEM for them to preload on each new machine they manufactured for you.  But due to some limitations in ConfigMgr (and our requirement to not do anything in MDT that isn’t supported by the ConfigMgr team), we had to do this in a less-than-optimal way.  We ended up with two task sequences:

  • One to set up the disk image
    • Format and partition the disk.
    • Apply the OS image.
    • Stash away various task sequence variable values to be restored later, so that the second task sequence can work, recognizing what’s already on the drive.
  • One to customize and boot into what’s already on the disk
    • Restore the stashed-away variables.
    • Apply patches and drivers offline.
    • Customize the OS settings (computer name, domain, etc.)
    • Install applications, software updates, etc.
    • Restore user state (for a computer replacement).

Because of the product limitations, there was no way to do this with a single task sequence.  And there was no way to initiate the second task sequence without a boot CD or using PXE.  That meant that the first task sequence would intentionally leave the disk unbootable (no partitions active) to ensure that the second task sequence was initiated next.  It worked and was supportable, but it wasn’t very pretty.

Fortunately, the ConfigMgr team was able to come up with a better solution in ConfigMgr R3 that they call “prestaged media”.  Using that, you can use a single standard task sequence to do this whole process.  The “create media” wizard now lets you create one large WIM file that contains both a boot image and an extracted OS image package, and that can be staged to the hard drive.  When that hard drive then boots, it contacts the MP and runs whatever task sequence you choose.  When that task sequence gets to the “Apply Operating System” step, it knows that the OS is already on the hard drive and just exits.  For more details on this whole scenario, see John Vintzel’s post at http://blogs.technet.com/b/inside_osd/archive/2010/04/29/prestaged-media-in-configuration-manager-r3.aspx.

So, back to the topic at hand:  What did we need to do to the MDT task sequence templates for ConfigMgr in order to support this new ConfigMgr R3 “prestaged media” capability?  It was almost embarrassingly simple:  We need to modify the “Format and Partition Disk” steps so that they wouldn’t execute if we were running from the disk.  This is a simple enough check to see if the task sequence variable “_SMSTSMediaType” is set to “OEMMedia”.  If it is, the formatting is always skipped so that the prestaged hard drive content is preserved.

That’s it – no other changes were needed in MDT 2010 Update 1 to support ConfigMgr R3.

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