Resource reservation for HA

[deepakjangra023]

Hello,

could you please tell me how i can calculate the resource amount to be reserved for HA in vSphere 5.

Thank You,

Deepak

[julienvarela]

Hi,

Please take a look on this post : vSphere HA admission control calculation for memory | VMware vSphere Blog - VMware Blogs

and here: vSphere Documentation Center

Hope it helps,

Regards,

Julien

[NuggetGTR]

Personally its all down to how the environment has been designed, There is no right or wrong answer. But generally in a cluster of say 5 Hosts you would want at least a single host worth of resources available.

HA protects against host failures so generally you want a host to cover the one lost, but if you look at your environment and look at the most utilised host as you want to take the worst case possible. what is that hosts current utilisation and then work out what % that works out to be for the cluster as a whole and then use that percentage as HA.

I do find it easier using whole hosts but I know some environments cant have that.

[Nick_Andreev]

If you want to protect yourself from a host failure, you will need use the Specify Failover Hosts policy.

Percentage of Cluster Resources Reserved policy is useful only if all your VMs are configured with reservations. Which is almost never the case.