When planning VMWare infraestructure, If I want a VM to work in HA, Do I have to reserve CPU, RAM, Storage ?? because if 1 vm is sleeping waiting for the master VM to fail, it's not ussing CPU, Am I correct?
Welcome to the Community - you are confusing two VMware products that provide High Availability - VMware HA and VMware FT -
VMware HA (High Availability) - Allows you to respond in the event of a host or VM failure by RESTARTING the VM on an available host - the key word is restarting meaning there will be a brief outage
VMware FT (Fault Tolerance) - Allows for the recovery of a VM in the event of a host or VM failure - in FT there is a VM tat is shadowing the primary VM and when that VM fails it will seamlessly take up the VM load with no downtime -
for most HA installations you do not have to set reservations of CPU. memory or storage -
and to add in FT the secondary VM is not sitting idle - it is not using as many resources as the primary VM but it is using some -