‘Environmental friendliness’ has been a common topic recently and now we are all aware of the fact that we should take better care of our planet. So, do we simply buy greener products? Is it really as simple as that?

In our personal as in our business lives we have a number of choices when it comes to choosing a product that will meet our needs and be environmentally friendly; from long-life light bulbs to partly eliminating the need for air travel by holding video conference calls, we can all help make a difference. One of the IT industries that has had most of the ‘green’ limelight is the storage industry. Hard disk drives use power to run and to cool down and hence it is important to maximise their utilisation. With organisations around the world generating extremely large volumes of data every day, the need to store, access and protect this information is paramount. So how can we ensure that data is suitably stored without unnecessarily harming the environment?
The efficiency of the product is the invisible, yet key, factor, as poor efficiency usually leads to higher power usage. Improve the efficiency of your storage infrastructure and suddenly your data centre will become greener and your TCO more appealing.

Although some vendors have focussed on the power consumption of data storage products when these are idle, much higher savings are to be realised by reducing the power requirements of those products which tend to be operational the majority of the time, because it is these devices that tend to have a greater impact on the energy bills.

So how can storage and data centre administrators get the best of both worlds? How can they make their infrastructure more efficient, more cost-effective and more environmentally friendly? Below are some considerations that will help put them on the right path.

Should disks be idle when not in use?
Hard disk arrays are mainly deployed in 24x7 operation environments such as database transactions for online retailers, web sites, e-mail servers, CCTV recordings, etc. In these cases the drives are providing round-the-clock services, and rarely have a chance to stop spinning. In addition most users require the full performance from the array, non-stop, which makes some heavily-marketed power-saving features disappointing in real-life applications.

One of the few instances when the arrays are often idle, is when they are part of the backup solution and hence the drives are written once and only occasionally accessed. In some disk-to-disk or disk-to-disk-totape backup configurations, data is written to the array just a few hours a day and is rarely read. In such circumstances, power-saving features such as idle disks become practical and effective.

Raise the efficiency, raise the green level
No matter how effective a product’s power-saving features are, if its overall efficiency is poor, it is not green. Every application has a unique requirement. This could be a priority such as performance, capacity, cost, data availability (redundancy), connectivity, etc, or a unique balance from those. The first priority should always be that the solution should fit the purpose and then improve the efficiency. By doing so, you may find the storage products that you are currently using, can be greener than the ones which claim to be “green” on the market.

Efficiency?
A bus full of passengers, is more efficient than a bus with just one passenger. Even though the full bus uses more fuel than the empty bus, the amounts of pollution and fuel per passenger make the full bus greener than the empty one.

There are 24 hours in a day (time, frequency and a smarter way of disk backup)
Efficiency is closely linked to maximisation of resources. Scheduled backups and other maintenance tasks should take place away from the peak working hours; they should utilise the scheduler function available on the disk arrays, to avoid affecting the service performance. In addition, analysis of the applications’ time patterns and scheduling the automated tasks, enable the arrays to be used around the clock in a more efficient manner.

Another way to ensure the infrastructure is more efficient, is by using the “snapshot backup” function to minimize the backup window. Ideally, users should choose the snapshot function, built-in and performed by the RAID system, rather than the host software. The data transfer is performed without the host software intervening, thus avoiding the unnecessary host CPU utilisation and occupation of the host access data bandwidth. As a result the disk backup no longer needs hours but just a few seconds. Moreover, the frequency of full backups and archiving can be decreased thanks to the use of snapshot backup. Therefore more energy is saved because the devices, not in use, can be turned off.

Sharing the storage
In a typical office with 50 users each PC (desktop or laptop) has a built-in disk drive and many store important data, which the IT manager needs to back up alongside the servers and any other shared data. It does not make sense to give each user a USB disk (or similar solution) to backup to; if each USB disk has 300GB capacity and uses 60W power, that corresponds to approximately 15TB of capacity and 3,000W of power requirements. Besides the management issue, some of the users may need more capacity, while others may only have small amounts of data to backup.
By backing up to a central disk array via the office network, all the unutilised storage is consolidated and can serve more users, while making better use of available capacity. If 50 users share a 15TB, 500W disk array, the individual power consumption is just 10W.
To make the most of centralised storage, when choosing a disk array, the IT manager should favour high performance and capacity in order to serve more and provide faster services. Performance is very important to increase efficiency and hence to make a product more environmentally friendly.

If we have two RAID systems and one performs four times faster than the other; one faster system can replace four slower systems. Instead of consuming the power and generating the heat of four slower systems, one faster system is much greener.

As a result the performance of disk arrays should be a major consideration when we think about green storage.

Different applications have different requirements
Some RAID products are purpose-built for data archiving, some are designed for 24x7, high-availability environments, and others which can fit a number of purposes, can be tuned and used in different application environments. These various types of storage products offer different levels of availability, security, performance and capacity. Due to the different types of disk drives used in high-availability storage, as opposed to archiving, the hardware, configurations and power requirements differ. Putting them side-byside to compare their environmental impact therefore, will only lead to misleading results.

For example, demanding environments such as database applications, should rely on disk drives with a high spindle speed (10,000 RPM or higher), and feature more disk drives in the configuration, so that more transactions per seconds can be performed. In addition, reliability is vital to allow 24x7 data availability. In this way, with the help of the cache memory present in the RAID controller, the RAID system can process vast amounts of small transactions coming in random order. On the other hand, disk drives used in data archiving need to offer large capacity and be lower in unit cost. The performance requirement here is not high, thanks to the snapshot backup functionality; reliability is not critical either for data archiving, as in many cases the drives are left idle.

This is why we cannot use a RAID system designed or configured for data archiving, in a highavailability environment. Can you imagine an online banking user having to wait for 30 seconds for the drives to ’wake up’ before being able to access their account details? When random transactions keep coming, all the disk drives are active, in order to provide the services, so the ability to have idle disks holds no appeal. On the other hand, putting a RAID system, designed and configured for 24x7 high performance operation, into the data archiving will feature a capacity/price ratio that will make the company CFO jump.

Can other off-line storage solutions be a greener choice for archiving?
Once data has been recorded on off-line media, it stays there without using additional power. This makes an off-line storage product a greener choice for archiving purposes, than massive disk arrays with powersaving features.

Please note, the archiving, disk backup (write-once-read-occasionally) and snapshot backup are all different in nature. They have their own unique requirements and provide different types of services. In many situations they are not overlapping each other and should be used in conjunction.

Invest in the right technologies and start saving the planet
In summary, your storage can indeed be greener, if you bear in mind the following factors:
• Understand your actual storage requirements and envisage the demands your organisation will
place on them, over the next three to five years.
• Ensure your storage infrastructure meets business requirements and priorities.
• Select the right storage product by considering the nature of the application, efficiency, performance, and technologies.
• Choose the storage vendor which provides a broad range of solutions.
• Choose a generic-purpose storage product to meet dynamic business requirements. A purposebuilt storage product may not be suitable when it is not used for its original purpose.
The extent to which a solution will avoid unnecessary power wastage is determined by the combination of business requirements, efficiency and performance.

Efficient storage is green storage.