Upgrading PXE boot performance of TFTP value size increasion.

Question

_{Friday, January 6, 2017 2:50 PM}

Hello guys,

I hope are some who made PXE performance of SCCM server.

Its enough to increase value on this registry key of TFTP? On network maximum transmission unit is 1500B.

IF value of RamDiskTFTPBlockSize increased more that MTU of network packages of network can be dropped.

IF value lower - can slowly downloaded.

Its enought to change this value on ALL pxe servers?

Location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\DP
Name: RamDiskTFTPBlockSize
TYPE: REG_DWORD
Value: 16384 (change radio button to decimal)

Or together (both) should i change this one in ALL pxe ?

Bcdedit -store c:\default.bcd -set {68d9e51c-a129-4ee1-9725-2ab00a957daf} ramdisktftpblocksize 16384

All replies (2)

_{Friday, January 6, 2017 3:10 PM ✅Answered}

You posted in CM2012 forum so this based on the assumption that this is your version. RamDiskTFTPBlockSize works with 2012 and increasing the value beyond the default will increase the TFTP speed, yes. Editing the registry is sufficient, no other modifications are needed. You will need to test this though since increasing the block size will cause fragmentation and some PXE clients do not support fragmentation and will fail.

If you upgrade to CB (1606+), you will also have access to RamDiskTFTPWindowSize which will also increase your TFTP speeds by modifying the window size (from a default of 1) and is compatible with more clients than modifying the block size.

You will need to edit the registry on the PXE DPs (all of them).

_{Friday, January 6, 2017 3:20 PM ✅Answered}

More information

/en-ie/sccm/osd/get-started/prepare-site-system-roles-for-operating-system-deployments#BKMK_RamDiskTFTP

http://ccmexec.com/tag/tftpwindowssize/

Gerry Hampson | Blog: www.gerryhampsoncm.blogspot.ie | LinkedIn: Gerry Hampson | Twitter: @gerryhampson