Green storage technologies, such as server virtualization, spin down, MAID, SSDs and tiered storage, can help organisations bring energy-efficient storage to their data centres. In this interview, SearchStorage.co.UK bureau chief Antony Adshead speaks with Clive Longbottom, service director at Quocirca, about what is driving green storage, as well as the technologies and processes that can help users create a green data centre.
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SearchStorage.co.UK: What is green storage and why is it an issue?
Longbottom: Green storage is pretty much what it says on the can. What you're looking for is storage that is far more energy efficient than we've had in the past. A lot of storage vendors will say, "Well, just buying the latest storage will be far more energy efficient than what has gone on before," but I think we've got to look beyond that.
The main thing when you're looking at green storage is that the data centre is becoming such a big energy drain that ensuring enough energy can be brought into the data centre is now an issue. So it's not just a case of 'Can we be seen to be green; can we have the tick mark against what we're doing?' It's a case of if we can't get enough energy into the data centre to run everything we're looking at building another one, and that starts at £5m, so this is a large expense which can go up to tens or hundreds of millions depending on the data centre required.
It's not just a green issue. It's very nice to move toward sustainability, but we are looking at this being a case of business continuity and being able to keep running as far as the business is required.
Power constraints can be a major issue. As we go forward and look at the government's figures, it's not going to be too long before the national grid will struggle to maintain enough power for everybody as existing fossil-based and nuclear power stations age and are taken offline. We're not replacing that quickly enough with big enough power-generating capabilities from renewables or other environments, so we will start to suffer brownouts.
Data centres have already looked at server virtualization. They've looked at how to make things more efficient there, but storage has tended to be left to one side.
SearchStorage.co.UK: What technologies and processes can reduce energy usage with regard to green storage?
Longbottom: What would seem to be fairly obvious is that a lot of high-level, enterprise storage is spinning 24x7 -- it doesn't spin down at all. So, if you have storage that you only have 30% storage utilisation of and it's continuously spinning, that's a lot of wasted energy. Just being able to look at being able to bring storage down when it's not being used -- stopping it from spinning -- is important. The problem there is if it isn't spinning and it is first-tier storage, then bringing it up from not-spinning to spinning has a latency issue and you're not going to get the data as fast as you would like to.
Therefore you have to look at how you can partition your storage in that environment, so virtualized storage becomes the key. Then you can say, 'OK, the partition of storage that I'm going to be using will be spinning 24x7. But those areas which are not being used at the moment, I can spin those down and only bring [them] up when I need elasticity of storage. As I need more storage, I bring more disks up to speed and bring them into the environment.'
That, in itself, is reasonably simple. We're seeing vendors come through with massive array of inexpensive disks [MAID], so instead of looking at the real high-level environment of the Symmetrix and so on, they're taking 3.5-inch disks, putting them all together and putting a controller around them to create a green environment that is spinning disks down as much as they can.
When looking at 3.5-inch disks the size of the platter, when spinning that up [it] takes more energy than spinning a 2.5-inch disk. If you move from 3.5-inch disks to 2.5-inch disks, you'll find that energy usage will go down.
Of course, the real energy saver is moving from spinning disk to solid-state disk [SSD]. With SSDs, you have no moving parts and energy usage falls by orders of magnitude. At the moment it is very expensive, and it still has less of a life than magnetic spinning disk. We are seeing advances that mean SSD has much longer life capabilities, but still you are looking at this as part of an advanced tiering strategy where you use SSD for data you have to have as close as possible.
Behind that, use 2.5-inch disks with spin down as much as you possibly can, and behind that use 3.5-inch disks and only spin them up when you need to get the data from them.
That can be a very cost-effective way of achieving green storage. The problem you have is if you have old storage, it's going to be energy inefficient; so green storage is a replacement strategy rather than an incremental strategy, an investment strategy rather than a save-money strategy for a total green environment.