Rightsizing is defined as changing the amount of resources allocated to a VM based on the Recommended Size for a VM. Recommended Size is the maximum projected utilization for the projection period from the current time to 30 days after the warning threshold value for time remaining. The warning threshold is the period during which the time remaining is green. If the warning threshold value for time remaining is 120 days, which is the default value, the recommended size is the maximum projected utilization 150 days into the future. While rightsizing a VM can reclaim capacity, the change in allocation may not equal the amount of reclaimable capacity.
Quantifying the Effect on Capacity Due to Rightsizing
- Reclaimable CPU Usage (GHz): If an oversized VM's CPU usage is 100MHz before rightsizing, removing vCPU's will not change its CPU usage and it should still be at 100MHz. This means there is no reclaimable capacity associated with overallocation of vCPUs. Reclaimable CPU Usage for oversized VM's will always be 0 MHz.
- Reclaimable Memory Consumed (GB): An oversized VM can have reclaimable memory only if consumed memory is greater than the new recommended size of the VM. The reclaimable memory capacity is the difference between consumed memory and recommended size.
- Increased CPU Usage (GHz): CPU usage of an undersized VM is expected to be the current CPU Demand. The difference between CPU Demand and CPU Usage is the expected increase in capacity utilized after rightsizing.
- Increased Memory Consumed (GB): It can be expected for consumed memory to increase by the same amount of memory recommended to add to an undersized VM.
In case of allocation model, you can directly pick the recommendation provided which is given as a part of the metric groups Summary|Oversized and Summary|Undersized.
Potential Cost Savings Calculation Detail
- Oversized CPU Utilization: $0 since Reclaimable CPU Usage (GHz) is always 0.
- Oversized Memory Utilization: Reclaimable Memory Consumed (GB) * Cluster Memory Base Rate.
- Oversized CPU Allocation: vCPU(s) to Remove * Allocation Cluster CPU Base Rate.
- Oversized Memory Allocation: Memory to Remove * Allocation Cluster Memory Base Rate.
Potential Cost Increase Calculation Detail
- Undersized CPU Utilization: Increased CPU Usage (GHz) * Cluster CPU Base Rate.
- Undersized Memory Utilization: Increased Memory Consumed (GB) * Cluster Memory Base Rate.
- Undersized CPU Allocation: vCPU(s) to Add * Allocation Cluster CPU Base Rate.
- Undersized Memory Allocation: Memory to Add * Allocation Cluster Memory Base Rate.
- Potential Savings metric (For VM) for Oversized VMs.
- Potential Increase metric (For VM) for Undersized VMs.