VMware FT Host limitation of 8 VCPU on enterprise plus license

[shovincyriac1]

Hi All,

I have a vmware FT cluster with 4 ESXi hosts and they are running with 5 VMs on them enabled with FT. Now i need to increase one of those VMs CPU to 8vCPU and the host will not be able to handle the other VM enabled with FT due to the host limitation of 8vCPU per host. How can i change this default value of 8vCPU limitation per hosts to overcome this as i understand that this ia the default value which is recommended by VMware  and this can be changed or increased?

[Duncan Epping]

https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.avail.doc/GUID-57929CF0-DA9B-407A-BF2E-E7B72708D825.html

[shovincyriac1]

Thank you , where i can get this option ? das.maxftvmsperhost? i dont find it in the cluster settings

[shovincyriac1]

i found this option in another blog, so this needs to be configured under cluster VMware HA settings. If these values are not present we need to add them and set the value to 0. I hope i am right?

[Duncan Epping]

No that is uncorrect, the value needs to be set to 0 when you want to disable the setting completely. You could set it to 12 or 15 for instance, which will allow you to have that number of FT enabled vCPUs running. Do note, the more you enable, the higher the impact on performance in the end, so monitor closely.

[nx_manuel]

Hi, 

is it supported for production to disable or use more than 8vCPUS per Host for the FT VM?
i have a 2 Node VSAN Cluster with WitnessAppliance and need to have one FT VM with 16vCPUS or 2 with 8vCPUS

thanks, br

[Duncan Epping]

yes it is supported, but it is not uncommon to experience performance degradation in those type of configurations as there's a huge amount of syncing that needs to happen.

[nx_manuel]

thats cool, i´m writing since a week with vmware support, they cant answer me this so im very thankfull depping!

what is with the enterprise plus license? it says 8vCPUS? still supported and ok?

thanks, 

br

[Duncan Epping]

Yes it is still supported, but if your performance is impacted and you phone support then support will probably tell you to lower the number of vCPUs.

[nx_manuel]

ok nice, then i can give it a try 

if the performance is too bad, what would be the next step to do?

2 FT VM with 8vCPUS each on one host? or maybe dual socket mobo with 2 physical cpus?

or buy 2 additional Nodes with ent+ license per host (prim+sec)

thanks

br

[Duncan Epping]

I am just re-reading the post, and let me clarify this, you will need more than 1 VM. A single VM can have a maximum of 8 vCPUs, and a single host can have a maximum of 8 FT enabled vCPUs. You can increase the host limits, but not the VM limits.

[nx_manuel]

ok, so i need to have 2 FT VM´s with 8vCPUS each on a single host to be supported.

if i know try to configure FT on two VM´s in my home lab there comes following error when i try to start the second VM:
"Insufficient resources to satisfy configured failover level for vSphere HA."

i disabled the max with "das.maxftvcpusperhost" in HA settings.

thanks

br

[Duncan Epping]

And you have sufficient unreserved resources from a CPU and memory perspective?

[nx_manuel]

ok sry my mistake, reduced mem and now its starting and working. (forgot that my homelab has not the same amount as my customer)

if this is supported, then i want really to thank you

config is now:
2-Node VSAN Cluster with 2x ent+ license, 
2 FT VM´s each 8vCPU (das.maxftvcpusperhost setting disabled)

thanks

br