Wednesday, September 1, 2010

Using SSD’s to Deliver Green Data Storage:

For those interested in driving environmental efficiency into their storage infrastructure SSD’s should be of particular interest. The boast from the SSD advocate is that an SSD can deliver environmental efficiency and performance without compromising either.

As a proof point of their position simply look at the relative device power consumptions. Obviously depending on the models being compared an SSD will consume about 1/5 of the power of a 15K RPM HDD. Depending on capacity, an HDD (15K, 300GB) will exhibit an efficiency index of about 22GB/W. An SSD such as RealSSD P300 from Micron posts about 100GB/W, based on their power specification of 2.1W; a 5 times improvement. Worth noting is that contrary to HDD's read and write power is the same.

Note: SSD’s do not generate the heat of an HDD so fans are eliminated creating additional savings on cooling costs. Those interested in learning more about the new Micron RealSSD P300 product check out Ray Lucchesi's blog

Another and perhaps more dramatic way to look at the performance/efficiency advantage of SSD is to consider a 15k RPM drive that can deliver about 12.5 IOP/W compared again to the recently introduced Micron P300 at 30,000 read IOP/W or 22,600 write IOP/W. So if SLA’s are suffering because of a lack in storage IOP’s otherwise known as IO bound storage, then SSD's are likely to be the solution. I say likely because care must be exercised to identify the source of the bottleneck because if the problem is not with storage then adding SSD’s will simply aggravate the problem, not solve it.

One of the common tactics employed by storage administrators is to increase storage IO performance for specific applications by short stroking high performance drives, sacrificing capacity for IOP's. Short stroking means that only the outer 20% or so of the platter is used for data storage limiting the movement of the actuator hence increasing the access density of the drive. While effective this is approach is expensive in CapEx as well as being a power, cooling and space hog.

Obviously reducing the working capacity of the HDD increases the usable $/GB of the drive and if the math is done this practice brings the cost of short stroked drives much closer to the $/GB cost of SSD’s. Adding to that reality is the reasonable working assumption that one SSD can deliver the IOP performance of 10 to 12 short stroked HDD's. So if your performance challenge is IOP’s or the lack thereof, think SSD.

However SSD are not the complete answer. The challenge is with the effective management of the data; to match the value and requirements of the data with the value and performance of the storage, easier said than done. Resolving this challenge and eliminating the administrative complexities common with storage tiering has been the catalyst driving automation.

There are many examples of such automation, FAST from EMC and Easy Tier from IBM are but two examples. However the more advanced performance tiering solutions such as Atrato’s ApplicationSmart™ has moved beyond automation to autonomic which as the definition implies “is the ability to manage or improve operation with little or no human involvement”. Intelligent and effective tiered management software is how you get rid of, or at least minimize management complexities.

This is what I mean by SSD’s enabling green storage by delivering performance without compromise.

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