Month: May 2016

Top vBlog & VMworld session voting

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It is that time of the year again! The annual top vBlog 2016 voting is open to show your appreciation for all the virtualization bloggers out there. I hope we at Cloudfix have created enough useful and diverse content in order to earn your vote. We sure love what we do, and we will strive to have another successful year of writing interesting blogs.

So click here to start your voting survey which will only takes a few moments. A big shout-out goes out to vSphere-land.com / Eric Siebert and sponsor VMturbo for making it all happen!

If you are willing to vote for us, we are listed in the main voting on the left side (blogs are listed in alphabetical order) and in the independent blogger section.

votevblog2016

In other news, the content catalog for the upcoming VMworld 2016 in Las Vegas is live! Make sure to check it out here! While doing so, it is also possible to cast your vote for your favorite sessions.

Our session (I will be speaking alongside Frank Denneman) is included in the catalog:

votesession2016

 

Thank you in advance for considering us!!

 

 

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Jumbo frames and the risks involved

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Even though the jumbo frame and the possible gain and risk trade-offs discussion is not new, we found ourselves discussing it yet again. Because we had different opinions, it seems like a good idea to elaborate on this topic.

Let’s have a quick recap on what jumbo frames actually are. Your default MTU (Maximum Transmission Unit) for a ethernet frame is 1500. A MTU of 9000 is referred to as a jumbo frame.

Jumbo frames or 9000-byte payload frames have the potential to reduce overheads and CPU cycles.

Typically, jumbo frames are considered for IP storage networks or vMotion networks. A lot of performance benchmarking is already described on the web. It is funny to see a variety of opinions whether to adopt jumbo frames or not. Check this blogpost and this blogpost on jumbo frames performance compared to a standard MTU size. The discussion if ‘jumbo frames provide a significant performance advantage’ is still up in the air.

There are other techniques to improve network throughput and lower CPU utilization next to jumbo frames. A modern NIC will support the Large Segment Offload (LSO) and Large Receive Offload (LRO) offloading mechanisms. Note: LSO is also referenced as TSO (TCP Segmentation Offload). Both are configurable. LSO/TSO is enabled by default if the used NIC hardware supports it. LRO is enabled by default when using VMXNET virtual machine adapters.

Risks?

Let’s put the performance aspects aside, and let us look into the possible risks involved when implementing jumbo frames. The thing is, in order to be effective, jumbo frames must be enabled end to end in the network path. The main risk when adopting jumbo frames, is that if one component in the network path is not properly configured for jumbo frames, a MTU mismatch occurs.
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