# Using SMB Compression with Windows 11

By Johan Arwidmark / August 6, 2021

While some SMB Compression code has been in Windows 10 for a while, it was not until Windows 11 and Windows Server 2022 it was implemented end to end. Anyway, that just had to be tested, so I quickly deployed a few Windows 11 machines and started doing some benchmarking.

In this test I'm using good old robocopy with the /compress switch, but you can also enable compress when mapping a drive letter, or when sharing a folder using PowerShell. Check out the -CompressData parameter for the the New-SmbShare and Set-SmbShare cmdlets, as well as the -CompressNetworkTraffic parameter for the New-SmbMapping cmdlet.

In between each test I rebooted both machines, to make sure nothing was cached in memory etc. messing up the benchmarking. In all tests a 16.6 GB VHD file was used and I also compared the performance on both VMs and physical machines. Here are the results:

##### Test 1 – Copy a large file without compression with RoboCopy on a VM

In this test, I was copying the VHD file between two VMs on the same virtual switch. Both VMs were configured with 2 vCPUs and 4 GB RAM. The virtual machine I copied the file from was smb-comp-002.

Command line: robocopy \\smb-comp-002\c$\Demo C:\Demo OSD-PC0001-Disk1.vhdx Time: 1m 31s Speed: 138 MB/s ##### Test 2 – Copy a large file with compression with RoboCopy on a VM Same as Test 1, but with adding the /compress switch to RoboCopy. Command line: robocopy \\smb-comp-002\c$\Demo C:\Demo OSD-PC0001-Disk1.vhdx /compress
Time: 57s
Speed: 296 MB/s
##### Test 3 – Copy a large file without compression with RoboCopy on a physical machine

In this test, I was copying the VHD file between two Dell machines on the same gigabit switch. The Dell machines were i7 CPU, 4 cores, and 32 GB RAM. The physical machine I copied the file from was chi-w10peer-008.

Command line: robocopy \\chi-w10peer-008\c$\Demo C:\Demo OSD-PC0001-Disk1.vhdx Time: 2m 38s Speed: 107 MB/s ##### Test 4 – Copy a large VHD file with compression with RoboCopy on a physical machine Same as Test 3, but with adding the /compress switch to RoboCopy. Command line: robocopy \\\chi-w10peer-008\c$\Demo C:\Demo OSD-PC0001-Disk1.vhdx /compress
Time: 2m 35s
Speed: 109 MB/s

#### Resources

For the Microsoft docs on the topic, check out this link: SMB Compression | Microsoft Docs