Simon Thorneycroft and Jonathan Hodgson

Longhorn networking enhancements

The Microsoft.com operations teams blog is definitely worth a read. This post details some of the testing they have been doing with regards to TCP/IP enhancements in Windows Vista/Longhorn and if the figures can be believed, they make some serious reading:

We set up one server in Bothell, WA and one in Santa Clara, CA (~22ms round-trip latency) and let the Devs have at testing with TTCP.

Now, TTCP pushes the limits of the stack, CPU, bus, network, etc, but that doesn't reflect the normal file transfers that happen as part of doing real work.  Since those file transfers create some of the more challenging scenarios for us, we put two new servers in WA and two in CA, all with GigE NICs.  Each data center has one W2K3 server and one Longhorn server.

From there we set up two Robocopy jobs to pull 20 1GB files from the servers in CA and drop them onto the servers in WA.  One job was run with W2K3 at each end and another was run with Longhorn.  All servers are the same HP DL385 Dual Core machines with 16GB RAM and GigE network uplinks.  Results:

• Pull with W2K3 at both ends (CA and WA) :  ~12Mb/s (includes SMB and TCP/IP tweaks)
• Pull with Longhorn at both ends:  >400Mb/s (default config...no tweaks)
• Pull of same 1GB files between two Longhorn boxes on same VLAN:  502Mb/s

So, I know, you're thinking, but I don't move a bunch of 1GB test files back and forth all day, I pull web logs from remote servers back to a central location for processing and that takes a significant amount of time. We thought the same thing so, for a real-world sample of something we do regularly we pulled a single hourly web log file (199 MB) from a www.microsoft.com server in CA back to a couple servers in the WA data center.  The WWW server in CA is a W2K3 box with GigE and we pulled the file across the wire with a W2K3 and Longhorn server in WA.  For a good view into the future we also put the file on a Longhorn server in CA and pulled from the same Longhorn server in WA.  Results: (represented in terms of time because when you get up to make a sandwich between file copies, this is how long you have):

• Pull from W2K3 in CA to W2K3 in WA:  ~2:12
• Pull from W2K3 in CA to Longhorn in WA:  ~0:12
• Pull from Longhorn in CA to Longhorn in WA:  ~0:04 (not much sandwich time)

Maybe combined with hot-patching feature, which should let all non-kernel updates occur without the need for a system reboot, Longhorn server might be more than the standard upgrade to run what new Microsoft product is tied to it.

If either product ever ships and looking at some of the Windows Vista bug reports that Robert McLaws put together charting the bug counts over time things still need some attention.