Faster PXE boot times in SCCM 1606 and later

A new feature introduced with SCCM 1606 was being able to modify the boot times for PXE. This is done by modifying the TFTP block and window size of the boot image RamDisk. This was originally implemented to help a admin over come network requirement. This allows us to make the PXE boot times much faster for my self this meant taking a 10 minute boot time all the way down to 30 second boot time. In order to make this change you need to create 2 registry keys on your PXE enabled DP.

Location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\DP
Name: RamDiskTFTPWindowSize
Type: REG_DWORD
Value: <customized window size>
The default value is 1 (1 data block fills the window) 


Location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\DP
Name: RamDiskTFTPBlockSize
Type: REG_DWORD
Value: <customized block size>
The default value is 4096 (4k). 

once you have added the registry keys you will need to restart  the Windows Deployment Service for the changes to take affect. 

Below is a table of results for each combination of Window and Block sizes created by Jorgen Nilsson of ccmexec.com. From the link you can also get more information on the settings as well as a Tool to create the keys and restart the Windows Deployment Service for you. 


Other information on this setting
https://technet.microsoft.com/en-us/library/mt627944.aspx#BKMK_RamDiskTFTP

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