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Trying to Discover the Bottleneck for Storage Vmotion Performance

JB Blanco
JB Blanco asked
Last Modified: 2018-12-19
I'm trying to determine where my bottleneck is as I'm seeing some very poor performance when doing a Storage vMotion migration (migrating VM's to a different host and datastore)

My Vmotion IP subnet is the same as my Management Subnet.( Esxi host management IP subnet on the same subnet as Vmotion)  Is this what is causing the problem?  It is the way this environment was setup before I got here.  Normally I would always separate the Vmotion vlan from the management vlan but that is the way it is here.  

Anyway Is here is my setup

Vcenter 6.5 u1b Build 6816762

Esxi hosts are mixed 5.0, 5.5 and 6.5

Is there a good tool to use to discover the bottleneck?  

I was googling and found iPerf that comes with Esxi 6.5 but ive never used it before.  

Any suggestions?  I really want to improve the storage vmotion performance

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Andrew Hancock (VMware vExpert PRO / EE Fellow)VMware and Virtualization Consultant
Expert of the Year 2017

It's best practice and recommended to have a completely different network for your vMotion/Storage vMotion network, with at least two nics for failover (resilience)  and Jumbo Frames enabled.

This could be dual physical nics (10GBe, 1GBe), and at least 2, 4, 6 to speed up transfer.

VLANs can be used if you have a method to analyse your VLANs and to check overall utilisation of the LINK (and VLANS inside).

BUT what is the issue, because vMotion/Storage vMotion is the real time moving of a VM in real time with no downtime, so do you just want to make it quicker.....

but if it succeeds why?

also bottlenecks in Storage, Read and Write can be an issue ?

Is it currently affecting production, and how often are your Storage vMotioning...

we use SDRS clusters, and VMs are moved round the datastores and we just let them move, we don't watch it!!!!

You can also look at your current performance using esxtop and vCenter Server.
JB BlancoSr Systems Engineer


We are not Svmotioning very often at all, good point.  I just noticed it since I am having to migrate some and I just noticed how painfully slow it is.  Yes as I mentioned I don't like the way they have it setup with Vmotion and management on the same vlan.  But that's the way it is and I don't think we can change it.  

But is there a tool of some sort I can use to discover the bottleneck more efficiently?  you said esxtop.  Is there a list of commands?
VMware and Virtualization Consultant
Expert of the Year 2017
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