DAteiserver are used in a multi-user environment central theme, due to home drives and, in many cases, folder redirection. Nowadays, virtual Windows Servers are often used for this purpose, but their configuration is not taken into account, and the default settings are simply used. With Server 2012 R2, the default is SMB 3.02, which is better than the previous versions (1.x, 2.x), but 2012 R2 offers more and should be used! VMware environments, in particular, do not use these features because they are disabled by default. Simply enabling them won't help either, as the VM needs to be configured accordingly.
Virtual Receive Side Scaling (vRSS)
„Virtual RSS“ is the "magic word" in Windows Server 2012 R2 and is an option in the network adapter settings. You can check whether it is enabled using PowerShell (PoSh). Either by Get-SmbServerNetworkInterface (Get-SmbClientNetworkInterface) or via Get-NetAdapterRSS and returns „True“ or „False“ as the value. Users of VMware will receive „False“ as the default response, meaning the feature is inactive. With Hyper-V and XenServer, the response is „True,“ meaning the feature is active.
Use the following PoSh command to enable RSS: Set-NetAdapterRSS -Name "AdapterName" -Enabled $True
What is RSS used for? Without RSS, all network I/O is handled solely via ONE CPU processed and With RSS, ALL CPUs used to process network I/O. This can significantly improve performance. In addition, server RAM is generally used to further optimize SMB traffic through caching. Therefore, more CPUs with RSS and, in general, more RAM are recommended.
Microsoft states that a modern CPU under under ideal conditions, 7 Gbps to the network and therefore cannot take full advantage of a 10 Gbps network. So Without RSS, it's 10 Gbps Networks are never fully utilized. If 4 CPUs were used, that would be 28 Gbit/s, but since the CPUs have other tasks to perform, I’m assuming about 30% CPU usage just for network I/O. That brings us to a good 9 Gbit/s.
If you need even more performance, you should SMB-Direct However, to do this, you need a RDMA a capable network adapter. However, I haven't seen a virtual adapter that can do that yet.
My minimum The recommended specifications for Server 2012 R2 as a file server with Active RSS are 4 vCPUs and 16 GB of RAM
References
- Virtual client-side scaling in Windows Server 2012 R2
https://technet.microsoft.com/de-de/library/dn383582(v=ws.11).aspx
