But how much data center energy usage is due to storage? This depends on the purpose of the datacenter in general or more specific the application (for example online transaction processing, multimedia content delivery, computationally intensive loads ), the accompanying i/o profiles and the storage design decisions on data integrity, availability, and reliability.
In the EPA Report to Congress on Server and Data Center Energy Efficiency it is suggested that, servers will on average account for about 75 percent of total IT equipment energy use, storage devices will account for around 15 percent, and network equipment will account for around 10 percent.
This estimated ratio is changing. The proportion of energy used by storage is increasing because of consolidation and virtualization of servers according the SNIA.
If we see the enormous growth of data being stored, 57% CAGR during 2006-2011, and that according to SNIA 25% of ‘digital universe’ is unique, but 75% are replicas / duplicates partly to ensure data integrity and survivability, partly wasteful, we have something to win in power consumption.
Green storage technologies must lead to less raw capacity to store and use the same data set but also in improving:
- Operational envelope (ASHRAE)
- Speed of Disks
- Use of appropriate RAID levels
- Disk utilization
For a better understanding of storage specific power and cooling data you also must be aware of the difference between full-load versus stand-by power versus idle situations.
With the Emerald™ Program, SNIA wants to provide public access to storage system power usage and efficiency. The SNIA has developed a test methodology and metric for measuring the power used by storage systems. There are two metrics being developed: An Active and a Passive test metric. Later they will also provide metrics or addendums to the existing metrics that take additional storage factors into account, e.g., data deduplication. To acquire the metrics requires a test plan that must be followed, and results will be posted on the SNIA Emerald website. The full SNIA Emerald is scheduled to be fully operational in the second half of 2011.
For more information read the SNIA tutorial on Green storage .