Power Modeling for Capacity Planning
We developed a model for the power consumption of the different storage controller components for various workloads characteristics. This work focuses on high-end controllers, as opposed to simple RAID disks.
The majority of the storage controller power consumption is attributed to the disk arrays. Of the power attributed to the disks, about two-thirds of the power required is used for spinning the platters; these platters are spinning even when "idle". The other third of the power is used to serve I/O requests.
In idle mode, the disk is spinning at its full speed, but no disk activity is taking place. Staying in the idle mode when there is no disk request provides the best possible access time since the disk can immediately service requests. But it is also the least efficient use of power.
* 12V is for the mechanical parts and 5V is for the electronics
How can we add power metrics to current performance metrics?
- Identify "power hooks" in the performance model. Some components can be relevant to both performance and power; others are not.
- Find the power consumption of each controller component.
- Compute per-disk power consumption in different I/O utilization levels using workload-dependant power measurements.
- Integrate the per-disk performance information from the model with the power utilization measurements.
