Shifting from energy avoidance to energy efficiency

June 14, 2009 – 8:33 am

Storage I/O trends

I’m continually amazed at the number of people in the IT industry from customers to vendors, vars to media and even analysts who associate Green IT with and only with reducing carbon footprints. I guess I should not be surprised given the amount of rhetoric around Green and carbon both in the IT industry as well as in general resulting in a Green Gap.

The reality as I have discussed in the past is that Green IT while addressing carbon footprint topics, is really more about efficiency and optimization for business economic benefits that also help the environment. From a near-term tactical perspective, Green IT is about boosting productivity and enabling business sustainability during tough economic times, doing more with less, or, doing more with what you have. On a strategic basis, Green IT is about continued sustainability while also improving top and bottom line economics and repositioning IT as a competitive advantage resource.

There is a lot of focus on energy avoidance, as it is relatively easy to understand and it is also easy to implement. Turning off the lights, turning off devices when they are not in use, enabling low-power, energy-savings or Energy Star® (now implemented for servers with storage being a new focus) modes are all means to saving or reducing energy consumption, emissions, and energy bills.

Ideal candidates for powering down when not in use or inactive include desktop workstations, PCs, laptops, and associated video monitors and printers. Turning lights off or implementing motion detectors to turn lights off automatically, along with powering off or enabling energy-saving modes on general-purpose and consumer products has a significant benefit. New generations of processors such as the Intel Xeon 5xxx or 7xxx series (formerly known as Nehalem) provide the ability to boost performance when needed, or, go into various energy conservation modes when possible to balance performance, availability and energy needs to applicable service requirements, a form of intelligent power management.

In Figure 1 are shown four basic approaches (in addition to doing nothing) to energy efficiency. One approach is to avoid energy usage, similar to following a rationing model, but this approach will affect the amount of work that can be accomplished. Another approach is to do more work using the same amount of energy, boosting energy efficiency, or the complement—do the same work using less energy.

Tiered Storage
Figure 1 the Many Faces of Energy Efficiency (Source: “The Green and Virtual Data Center” (CRC)

The energy efficiency gap is the difference between the amount of work accomplished or information stored in a given footprint and the energy consumed. In other words, the bigger the energy efficiency gap, the better, as seen in the fourth scenario, doing more work or storing more information in a smaller footprint using less energy.

Given the shared nature of their use along with various intersystem dependencies, not all data center resources can be powered off completely. Some forms of storage devices can be powered off when they are not in use, such as offline storage devices or mediums for backups and archiving. Technologies such as magnetic tape or removable hard disk drives that do not need power when they are not in use can be used for storing inactive and dormant data.

Avoiding energy use can be part of an approach to address power, cooling, floor space and environmental (PCFE) challenges, particularly for servers, storage, and networks that do not need to be used or accessible at all times. However, not all applications, data or workloads can be consolidated, or, powered down due to performance, availability, capacity, security, compatibility, politics, financial and many other reasons. For those applications that cannot be consolidated, the trick is to support them in a more efficient and effective means.

Simply put, when work needs to be done or information needs to be stored or retrieved or data moved, it should be done so in the most energy-efficient manner aligned to a given level of service which can mean leveraging faster, higher performing resources (servers, storage and networks) to get the job done fast resulting in improved productivity and efficiency.

Tiering is an approach that applies to servers, storage, and networks as well as data protection. For example, tiered servers include large frame or mainframes, rack mount as well as blades with various amounts of memory, I/O or expansion slots and number of processor cores at different speeds. Tiered storage includes different types of mediums and storage system architectures such as those shown in figure 2. Tiered networking or tiered access includes 10Gb and 1Gb Ethernet, 2/4/8 Gb Fibre Channel, Fibre Channel over Ethernet (FCoE), iSCSI, NAS and shared SAS among others. Tiered data protection includes various technologies to meet various recovery time objectives (RTO) and recovery point objectives (RPO) such as real-time synchronous mirroring with snapshots, to periodic backup to disk or tape among other approaches, techniques and technologies.

Technology alignment (Figure 2), that is aligning the applicable type of storage or server resource and devices to the task at hand to meet application service requirements is essential to archiving an optimized and efficient IT environment. For example, for very I/O intensive active data as shown in figure 2, leveraging ultra fast tier-0 high-performance SSD (FLASH or RAM) storage, or for high I/O active data, tier-1 fast 15.5K SAS and Fibre Channel storage based systems would be applicable.

For active and on-line data, that’s where energy efficiency in the form of fast disk drives including RAM SSD or FLASH SSD (for reads, writes are another story) and in particular fast 15.5K or 10K FC and SAS energy efficient disks and their associated storage systems come into play. The focus for active data and storage systems should be around more useful work per unit of energy consumed in a given footprint. For example, more IOPS per watt, more transactions per watt, more bandwidth or video streams per watt, more files or emails processed per watt.

Tiered Storage

Figure 2 Tiered Storage: Balancing Performance, Availability, Capacity and Energy to QoS (Source: “The Green and Virtual Data Center” (CRC)

For low-performance, low activity applications where the focus is around storing as much data as possible with the lowest cost including for disk to disk based backup, slower high capacity SATA based storage systems are the fit (lower right in figure 2). For long-term bulk storage to meet archiving, data retention or other retention needs as well as storing large monthly full backups or long term data preservation, tape remains the ticket for large environments with the best combination of performance, availability capacity and energy efficiency and cost per footprint.

General approaches to boost energy efficiency include:

  • Do more work using the same or less amount of power and subsequently cooling
  • Leverage faster processors/controllers that use the same or less power
  • Apply applicable RAID level to application and data QoS requirements
  • Consolidate slower storage or servers to a faster, more energy-efficient solution
  • Use faster disk drives with capacity boost and that draw less power
  • Upgrade to newer, faster, denser, more energy-efficient technologies
  • Look beyond capacity utilization; keep response time and availability in mind
  • Leverage IPM, AVS, and other techniques to vary performance and energy usage
  • Manage data both locally and remote; gain control and insight before moving problems
  • Leverage a data footprint reduction strategy across all data and storage tiers
  • Utilize multiple data footprint techniques including archive, compression and de-dupe
  • Reduce data footprint impact, enabling higher densities of stored on-line data

Find a balance between energy avoidance and energy efficiency, consolidation and business enablement for sustainably, hardware and software, best practices including policy and producers, as well as leveraging available financial rebates and incentives. Addressing green and PCFE issues is a process; there is no one single solution or magic formula.

Efficient and Optimized IT Wheel of Oppourtunity

Figure 3 Wheel of Opportunity – Various Techniques and Technologies for Infrastructure Optimization (Source: “The Green and Virtual Data Center” (CRC)

Instead, leverage a combination of technologies, techniques, and best practices to address various issues and requirements is needed (Figure 3). Some technologies and techniques include among others infrastructure resource management (IRM), data management, archiving (including for non-compliance), and compression (on-line and off-line, primary and secondary) as well as de-dupe for backups, space saving snapshots, and effective use of applicable raid levels.

Green washing and green hype may fade away, however power, cooling, footprint, energy (PCFE) and related issues and initiatives that enable IT infrastructure optimization and business sustainability will not fade away. Addressing IT infrastructure optimization and efficiency is thus essential to IT and business sustainability and growth in an environmentally friendly manner which enables shifting from talking about green to being green and efficient.

Learn more on the tips, tools, articles, videos and reports page as well as in “Cloud and Virtual Data Storage Networking” (CRC) pages, “The Green and Virtual Data Center” (CRC) pages at

Ok, nuff said.

Cheers gs

Greg Schulz – Author Cloud and Virtual Data Storage Networking (CRC Press), The Green and Virtual Data Center (CRC Press) and Resilient Storage Networks (Elsevier)
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