I read a great blog post a while ago from Jason Boche titled Jumbo Frames Comparison Testing with IP Storage and vMotion. The results of the tests showed at best marginal gains to be had from using Jumbo Frames with 1Gb/s NIC’s on ESXi 4.1. Based on reading this, and a lot of discussion that came out of PEX 2012 regarding Jumbo Frames I decided to conduct my own tests to see if the results were any different when using modern 10G switches and NIC’s. Some of the results were not what I expected.
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Many companies are starting to run Jumbo Frames across their network to improve performance, especially as 10Gbe infrastructures become the norm. When you’re making a change such as implementing Jumbo Frames it’s important to evaluate what possible implications it might have. One such implication that I wasn’t aware of till today is a possible problem with Jumbo Frames when used on your VMKernel Management Network with vSphere 5.0 and vSphere HA. Duncan Epping at Yellow-Bricks.com posted an article describing the situation titled “No Jumbo Frames on your Management Network” and pointing to a VMware KB article 2006729. The KB article only mentions Jumbo Frames in a very small not right at the very bottom. I would strongly recommend you read Duncan’s post for more information.
I personally haven’t come across this problem even though I run Jumbo Frames across my entire network in my lab, including on the VMKernel Management Network used for HA. However I have run into other problems with Jumbo Frames support in the VMware VMXNET3 Driver when using the VMware Tools version from ESXi 5.0. My advice is that you should have a thorough test plan whenever you are making a significant infrastructure change, and evaluate all the pro’s and con’s. There are significant advantages when running Jumbo Frames on 10G networks, and even advantages on 1G networks, although not the same magnitude.
This post first appeared on the Long White Virtual Clouds blog at longwhiteclouds.com.
By Michael Webster +
There is a bug with the new version of VMware Tools that comes with vSphere 5.0 GA when using VMXNET3 and Jumbo Frames on Windows. The bug can cause performance problems or instability and loss of connectivity. VMware KB 2006277 explains the problem and offers a workaround. It is expected that this problem will be fixed in ESXi 5.0 Update 1. This will be important for customers thinking of migrating to vSphere 5.0 that normally update VMware Tools immediately as part of the upgrade process and customers wanting to implement VMXNET3 and Jumbo Frames.
This post first appeared on the Long White Virtual Clouds blog at longwhiteclouds.com.
By Michael Webster +
