By default, System Center Configuration Manager 2012 use a small TFTP block size, 512 bytes. This behavior is set to be compatible with all network configuration, but the result is that the PXE boot speed can be slow using Operating System Deployment with SCCM.
We can resolve this problem by adding a registry key on the PXE Server. Modification must be made on PXE Distribution Point.
To increase the PXE boot speed, we need to modify TFTP Block Size.
- In the registry editor:
- Path : HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\DP
- Name : RamDiskTFTPBlockSize
- Type : REG_DWORD
- Value : 16384 (decimal)
Note: 16384 is the maximum supported value. If it is bigger, you can have corrupted data. However I recommend to do some test with values :4096, 8192, 16384. Depends on your network configuration, a lower value can be used.
- Restart the Windows Deployment Services Service. (WDS)
You can have more information about SCCM and PXE here.