Doing your Byte
Published May 17, 2007 at 4:45 pm · Filed under Features
Electronic document management systems are often promoted for their paper-saving properties. Steve Tongish, director of marketing (EMEA) at Plasmon, argues that environmentally responsible businesses should also evaluate the technologies used for archiving data, as these can have a significant effect on power consumption and carbon emissions.
Climate change is one of the most important issues facing mankind in the 21st century. There is growing recognition that traditional energy supplies are neither endless nor secure, and greater understanding of how their use is harmful to our environment. As a consequence, governments, corporations and individuals are taking action to curb excessive use of energy resources.
A major consumer of electrical power within businesses is the IT infrastructure, so the energy consumption of individual IT products is under greater scrutiny than ever before. One area where significant green gains can be realised is in the archival storage of business information.
Consider your archive
Industry regulations, corporate policies on risk management and a competitive need to exploit valuable information assets mean that organisations are being required to retain strategic business records for many years and even decades.
Archive records are characterised by a number of key attributes and requirements. Unlike data that is being actively created or modified, archive documents are static and in many cases must be carefully protected against alteration. Access to archive data is different to that of active data since documents must be available for long periods of time and recall can be random and infrequent.
Archiving presents IT administrators with the opportunity to develop a strategy to meet their authenticity, longevity and access requirements. Through careful choice of storage technology, they can also reduce the energy needed to power archive systems and so reduce carbon emissions.
There are several technologies to choose from, each of which has its own performance attributes and energy consumption profile. To demonstrate the environmental consequences of choosing a particular technology, consider the varied performance of magnetic and optical disks.
Magnetic disk RAID arrays provide high performance in both capacity and speed of access. However, to maintain the integrity of the disk archive, electrical power is continuously required to spin the disks. As a result, this type of archive is particularly power hungry.
In contrast, optical storage technology uses laser technology to write archive data to a Phase Change disk. In enterprise archiving applications, these disks are integrated into an automated library with a small amount of magnetic disk, which acts as cache and enables the archive to be recognised as network attached storage. Energy is required to power the magnetic disk element of an optical archive appliance, with a modest amount of additional power required when specific read and write requests are made to the optical media.
Optical vs magnetic disk
As individual magnetic disk archive technologies vary considerably in the amount of power they require, we selected a popular 40TB (terabyte) network attached magnetic disk archive with average(ish) power consumption. We also selected an industry standard 40TB network attached optical archive system.
In order to estimate the total electricity requirement for the archive over a 10-year period, we took into account the electricity required to power the storage system and the power needed to provide cooling, circulation, humidification and overhead for the Uninterrupted Power Supply (UPS) infrastructure. Since most professional archives are powered down only for system upgrades or maintenance, we assumed constant operation throughout the year.
The electrical power required to operate the archive systems varied dramatically. With a conservative 6% annual compound growth rate in the cost of electrical supply to London factored in, the electricity cost of running the magnetic disk system over ten years was £226,200, compared to just £16,159 for the optical system.
In other words, the magnetic disk system was almost 14 times more expensive to power than an optical archive. This is not surprising when you consider that the optical solution uses only a small amount of spinning magnetic disk (as a high performance cache) and a very power efficient optical media library. In contrast, the magnetic disk system spins and cools the disks even when there are no users accessing the archive.
To put this in environmental, rather than financial, terms, the annual carbon emissions of the optical archive would amount to four tonnes, compared to 62 tonnes for the magnetic disk system. Given that the average carbon emission of a UK resident is 11 tonnes annually, the magnetic disk archive has the same carbon footprint as nearly six people, whereas the optical system has one of less than half of a person.
These figures are even more striking when you consider that we selected a magnetic disk archive with ‘average’ power consumption and that many installations are duplicated for reasons of business continuity.
Conclusion
Selecting an archival storage technology requires careful consideration of factors such as performance, record authenticity, data longevity, system maintenance, administration, acquisition, operating costs and, increasingly, energy consumption.
This analysis looked in detail at just one factor, but the conclusion is obvious: archive strategies that rely solely on magnetic disk technologies will be much more expensive to operate and are responsible for significantly higher carbon emissions.
Steve Tongish is director of marketing (EMEA) at Plasmon. The full white paper can be downloaded from www.udoarchiveappliance.com
