ESXi host memory best practices

[jdwyeriv]

Hello All,

We currently run vSphere v5.5 clusters with BL460c Gen8s with 164GB of memory.

We are looking to up that memory amount, but I wanted to check on best practices for vSphere clusters and ESXi hosts.

Concerned about the VM to Host ratio being too high. Currently averaging 30 VMs per host on the Gen8s.

Is it better to scale across or up?

Input is much appreciated.

Thanks.

[schepp]

Hey,

two quick things that come to my mind to consider:

1. how many hosts do you have? When scaling up in RAM and VM/host like that, do you have enough hosts to tolerate a host failure?

2. take a look at the vCPU to phyiscal core ratio. When that ratio goes too high you might run into problems because your physical cores have to schedule the vCPUs and your applications may need to wait for CPU time. Check esxtop to see if you already experience high wait times: http://www.yellow-bricks.com/esxtop/

Tim

[Icecubbe]

Hi,

Tim got it spot on.

Our BL460c Gen 8 Blades was running 256GB RAM but CPU ratio was very low and we could accommodate a many for VMs. We have upgraded to 512GB Memory and running +-39 VMs but some of them are huge when looking at resource usage.

Will depend a lot on the CPUs being used as well. Also check how much CPU resources are being used.

Hope the info helps.

Kind Regards