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Best configuration for 6 geographically separated nodes

  • 5 May 2014
  • 7 replies
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Hi guys, I'm designing a Nutanix infrastructure, and I'm struggling with the most optimal configuration given the specs Specs: - 2 sites (80 km apart, latency
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Best answer by TheDude 6 May 2014, 20:37

I'd configure them as 2 seperate clusters (1 per site) today since stretch cluster support isn't yet available today and run DR between them. Then, once stretch cluster support is released (can't quote a date :P) all you'll need to do is "stretch" the nutanix clusters and merge your vSphere cluster (as well as configure DRS affinity groups, etc.)

The main reason for doing this is for a few reasons:
  • If the inner-site link were to fail you'd lose quorum for 1 site
  • Once strech clustering is released its a simple upgrade and single command to stretch. If it was configured as a single cluster today you'd essentially have to "remove" one full site from the cluster and then stretch
  • You negate and write latency issues as cassandra and writes would need to currently cross the site link
Feel free to reach out with any other questions!

Steven Poitras
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Userlevel 2
Badge +12
I'd configure them as 2 seperate clusters (1 per site) today since stretch cluster support isn't yet available today and run DR between them. Then, once stretch cluster support is released (can't quote a date :P) all you'll need to do is "stretch" the nutanix clusters and merge your vSphere cluster (as well as configure DRS affinity groups, etc.)

The main reason for doing this is for a few reasons:
  • If the inner-site link were to fail you'd lose quorum for 1 site
  • Once strech clustering is released its a simple upgrade and single command to stretch. If it was configured as a single cluster today you'd essentially have to "remove" one full site from the cluster and then stretch
  • You negate and write latency issues as cassandra and writes would need to currently cross the site link
Feel free to reach out with any other questions!

Steven Poitras
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I have been digging into the Availabilty Domains feature, and I come to the same conclusion. It simply doesn't have site awereness today and as such, cannot handle split brain scenarios very well.If I have two blocks on one site and a third on a second site, the cluster will go down if the first site fails, since there is only one surviving node. In a split brain scenario, only the first site will survive.Steven, can you tell a bit more about the anticipated process to merge both (site-local) clusters into a single stretched cluster? How will that work, and what will happen to data on those two (site-local) clusters?
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I can't give too much detail since nothing has been released yet. However, I can say they will still operate as two distinct clusters just "stretched" -> Hint: think remote RF :)

Shoot me an email if you want to discuss further
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That is smart! That'll allow you to re-use whatever locality the cluster design allows for stretching. Would love to be briefed about it to optimize my current design for this upcoming feature!
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Hi,

As of today is the Metro Cluster (Stretched Cluster) with VMware is supported ?

I understand that as per this tread the solution is a "stretched" RF ie: two distinct cluster.

If you loose a complete site will the second site restrart all the VM automatically (as of today ?)

Thx

JD
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Stretched Cluster isn't available with Nutanix 4.0.1.1, the latest release. It might be released as part of v4.1. As I do not work for Nutanix, I cannot give any further information.
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Hi,As of today is the Metro Cluster (Stretched Cluster) with VMware is supported ?I understand that as per this tread the solution is a "stretched" RF ie: two distinct cluster.If you loose a complete site will the second site restrart all the VM automatically (as of today ?)ThxJD

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