Monthly Archives: March 2012

Windows Server 8 NIC Teaming tips

Some highly knowledgeable folks at Microsoft recently shared some very valuable tips during the recently concluded MVP Summit. This blog is a small sample of thse tips.

Prior to Windows 8, NIC Teaming has been a feature never officially supported by Microsoft. It was a third party offering from an OEM/IHV/ISV and all support for the feature had to be provided by the third party. I personally have spent considerable time debugging situations where a system start up service I wrote had issues. It turned out that my service could not connect to the Domain Controller because the NIC team was still in the forming stage and had not yet completed its initialization.

Windows Server 8 natively supports NIC teaming. Here are the highlights and tips:

  • NIC teams can only be formed between homogenous NICs. So two 1GB NICs can be teamed, or two 10GB NICs can be teamed, but you cannot team a 1GB and 10GB NIC.
  • If the individual NIC members each support Receive Side Scaling (RSS), the NIC team also supports RSS. Hence it is a good idea to team NICs that support RSS. The resulting NIC team is also highly capable and does not lose any functionality.
  • If the individual NIC members each support RDMA, the resulting NIC team does NOT support RDMA. Given how Windows 8 SMB 2.2 natively supports RDMA without modifying applications, it is a bad idea to team NICs with RDMA capabilities, and where the interconnect (routers, etc) also supports RDMA

Windows 8 client/server file traffic approaches DAS speed

Traditionally, client server file traffic has always been considered to be very slow, as compared to file access when the file is placed on Direct Attached Storage (DAS).

Note that clients as used in this particular blog apply to not just clients as in laptops, but also server to server communications where one of the servers acts as a client. For example, a laptop connects across the Internet to an IIS Server, and the IIS Server fetches some files from a file server to satisfy the client request.

Microsoft just posted a white paper showing some very interesting performance benchamrsk for file access over SMB2.2 when both client and server are running Windows 8. The paper can be found here

A one line summary of the paper could be “client/server file access speeds go from high twenty percent to almost parity with speed of Direct Attached Storage” ; and in particular from say 28% to 97%.

Note that the “client” used in the test had 48GB RAM, and while I admit that the test involved non cached I/O, so the extra RAM was not used for caching, it is still worth noting that this is not a typical client as in a laptop client. This is more like a server behaving as a client.

Nevertheless, this makes the client/server world more interesting, and also makes a compelling case for upgrading to Windows 8. Especially so when you can simultaneously upgrade all your servers e.g. SQL, IIS, and NAS file servers to be Windows 8. Upgrading just a single server does not help much, since in that case, the client is still an old client that does not speak the SMB 2.2 protocol.

Windows Server 8 encrypts user data in flight between client and server

I have been at the MVP Summit in Redmond, and have been carefully noting “advances” between Windows Server 8 Developer Preview (made available at the BUILD conference in Anaheim) and the newer Windows Server 8 Beta build made available on Feb 29 2012.

One new feature is that the SMB 2.2 protocol used for client/server file data exchange now allows for data encryption. Both the client and the server need to be running the new SMB 2.2 protocol – so this means both need to be Windows 8, or the Server needs to be a fairly new one from a vendor that has implemented SMB 2.2

Verticals such as the health care industry should find this particularly useful. The huge overhead of using a solution such as IPSEC can now be avoided.

Details such as what encryption algorithm, as well as performance characteristics of this encryption will be blogged about, once I perform some experiments with the beta bits.

The only public Microsoft information as of today is at