Sunday, June 19, 2011

Windows 7 SP1 bring increase to Realtek RTL8102/8103 networking performance

One of the items on my To-Do list has been bringing the lab's file transfer speed up to snuff. Samba has never been a very willing component of a fast network, seemingly requiring different tweaking for every different system to get it's speed to be close to Window's smb performance. Adding ZFS to the mixture adds difficulty, as anyone who's tried to benchmark ZFS knows.

I did find out a combination that makes Samba fly in my environment, I'll share that shortly in a separate post.

Whilst performing iometer tests across the network, I noticed one of our ASUS-based systems was slower than the others, giving 80 MBs transfers compared to the 100-114 MBs transfers that I was receiving from identical machines. These boards use a Realtek 8102/8103 PCIe on-board network card.

That's when I noticed this machine hadn't applied Windows 7 SP1 yet.

After installation, I'm now receiving the same speed as the rest of the systems in the lab. I'm not sure if it was an updated driver, changes to the network subsystem, or something else - Unfortunately I don't have time to investigate.

However, if you're not receiving full network speed from your Win 7 machine, and you haven't applied SP1 yet, try that first.

Here's my quick test results:

Using iometer 1.1-devl, 128 writers, and the 4k sequential read test. 5 min ramp-up time, and the test runs for 15 minutes. I used a small 4 Meg test-file to remove ZFS from the equation (this small file is quickly cached in RAM, removing the server's disk speed from the test)

Before SP1
19617 IOPS  80 MBs 6.5 ms Avg IO

After SP1
25177 IOPS 103 MBs 5.1 ms Avg IO

(I'm receiving nearly the same speeds for write as well)

That's quite the difference. With some further tweaking, I'm getting my Win 7 SP1 machines to saturate the network link to 99% utilization using a FreeBSD9/Samba35/ZFS28 SAN.

Since we move a lot of data across this network each day (system images, data recovery, etc) it makes for happier technicians.

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