EVC on a Cluster with identical hardware

[MKguy]

Should I bother enabling EVC on a 2 host cluster with identical hardware and identical BIOS settings? DRS will NOT be enabled, but we will manually VMotion

VMs if maintenance on a host is required.

I searched for recommendations and caveats to consider in the VI 3.5 admin and resource management guide, but didn't found anything particular for this case, so I'm pondering whether I should/can enable this feature. (I'm currently inclined to not enable it.)

Both hosts are HP DL380G5 with Xeon 5420 CPUs and ESX 3.5 U2 build 113339.

[ChrisDearden]

Are you planning on expanding the cluster at all ? It coudl save you a lot of hassle later down the line if you where to attempt to add a non vmotion compatible host ?

[MKguy]

I thought about that as a point for enabling it too, but I don't know whether we will add more hosts in the future (which will probably have newer CPUs and instruction set features) to it or if we will stick with 2 host Clusters only.

Can anything go wrong anyways with EVC being enabled or will it have any impact on the performance/some other things of our hosts?

What if I want to VMotion a VM between a cluster member and a host outside of the cluster?

[jfchevrette]

Can anything go wrong anyways with EVC being enabled or will it have any impact on the performance/some other things of our hosts?

I would like to know too as we are currently expanding our cluster and wondering if enabling EVC will have any sort of performance impact. There must be a reason that feature isn't enabled by default?

[Texiwill]

Hello,

It is enabled on my two node cluster. This will help when you upgrade hardware in the future. As for it impacting performance. So far I have yet to see an issue. EVC specifically helps when you add new processors (6core, etc) or when you upgrade to newer boxes with newer processors within the same family of processors.

Best regards,

Edward L. Haletky

VMware Communities User Moderator

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Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.

CIO Virtualization Blog: http://www.cio.com/blog/index/topic/168354

As well as the Virtualization Wiki at http://www.astroarch.com/wiki/index.php/Virtualization