Making the case for solid-state drives requires knowing price per I/O, gigabyte

Presenting a case for solid-state drives (SSDs) to upper management requires a research on cost per gigabyte and price per I/O.

Storage administrators hoping to make a case for solid-state drives (SSDs) to their CIOs or CTOs inevitably need to justify the expense. They can analyze the cost equation from a number of different vantage points; the goal is to be able to compare their current actual cost per gigabyte and cost per I/O against the projected price for SSDs. More importantly, data storage managers need to promote a different line of thinking when arguing the merits of solid-state storage, according to Mark Peters, a senior analyst at Milford, Mass.-based Enterprise Strategy Group.

In this expert Q&A, Peters discusses the data points that a storage administrator should collect and the research that a storage administrator should have in hand when making the case for various types of solid-state storage. You can read the transcript that follows or listen to the MP3 file below.

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Making the case for SSDs requires new line of thinking
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What types of problems is solid-state storage best suited for?

Mark Peters: I think there are really three important problem areas. The first is that people are thinking of solid-state storage in terms of performance. I would like the listeners to think more broadly. As we develop over the years, it's going to be more that solid-state is not a problem solver; it's more just a place where you have all your I/O served. So in the future, SSD will be about I/O, I/O, I/O, even though today it's about performance.

Second, there is the fact that solid-state can help to get the power and cooling down. And, third, and very important on everyone's list, particularly in these times, is you can use a judicious amount of solid-state to actually drive down the overall cost of storage.

What sorts of data points can a storage administrator pull together to make an effective case for solid-state drives to upper management?

Peters: It's always going to depend on what your upper management likes, I suppose. But, there are some things that might help people. The first one is case studies. Many vendors have solid-state tools that you can go onto online that do what-if analysis. In other words, if I install this many solid-state drives, what impact will it have both on cost and performance?

Second, make sure that you understand the varying implementations of solid-state because, for example, these days auto- tiering and using solid-state storage as caching are both tools that make it a lot easier to implement and a lot easier to justify.

And third, you're going to want to know the cost per I/O of what you're about to implement, but more importantly, understand your real cost per gigabyte and your real cost per I/O of what you're currently doing. That comes from aspects such as utilization, power, space, that sort of thing.

Is cost still the major drawback to SSDs? And how can a storage administrator justify the added expense?

Peters: I think cost is still the first thing that flashes through someone's mind when they hear "solid-state". So, yes, it is still a big factor. The big challenges today are: are they using it for all sorts of I/O? And what percentage are you going to use and in what manner? Storage tiering helps with this, but you do need to do some work to help justify the expense, and to do that, you need to start thinking differently.

Here's an analogy: Often I will stand up and ask people, "Would you pay $20 for a gallon of gas?" This is about going to your upper management and asking for a lot more money. And many people will just naturally say "no" without being told that your mileage per gallon or the number of people you can get in the car or many other factors will improve if you actually buy the more expensive gas.

That's the way you need to approach this. You have to get people to go beyond the obvious and think about what it actually means -- the same or improved performance with lower cost. Justifying the added expense shouldn't be a problem. I would say in the majority of cases, the added expense amounts for just for a fraction of the storage, which should actually not be an added expense overall.

Is it fair for people to compare the price per gigabyte of hard disk drives versus SSDs?

Peters: Sure, it's fair to compare. But, it depends what you're going to do and what you're actually storing. There will be some instances where you can compare all you like, but cost doesn't matter, such as an airline reservation or something like that. In that case, you're using it as an absolute tier for the absolute best performance, and, therefore, cost is not irrelevant, but it's certainly low on the list.

In other areas, if you're using solid-state disks as a caching device for Web videos or whatever's popular at that particular moment, you may have a different view of this.

So, is it fair to consider the price per gigabyte versus hard drives? Absolutely. But, is it the only way, the main way, the optimum way? Absolutely not.

Are there different types of solid-state devices? Should the storage admin do some homework and suggest a particular type of SSD to upper management?

Peters: Categorically, yes. There are many different types of SSDs out there. Typically you'll hear about SLC and multi-level cell (MLC), different capacities and different capabilities. There are also varying places that SSD can go. It might be as a drive in the actual storage array. It might be as an appliance, serving across multiple arrays. It could be up into the server. It could be PCI Express. There are all different types and places, and they all bring slightly different things to bear.

No one thinks it's strange to have a hierarchy of disk or a hierarchy of storage in a broader sense. So, it's quite conceivable that many places will actually have a number of different solid-state devices employed to do different things. It makes perfect sense. If you're only going to start small, you need to figure out what's most valuable to you. But again, it doesn't matter whether it's a tape drive, a disk drive, a solid-state drive, a server, a piece of software, or a new phone system for your house. You're going to do the homework for all of them, and it's exactly the same for SSDs.

What's the single most important piece of advice you'd like to leave with storage administrators who are trying to make a case for solid-state drives to their CIOs or their CTOs?

Peters: It's a big challenge to get anyone who's not close to this to understand it well. You need to get them to think with their head, not their heart. We have decades of thinking that the only thing that matters is cost per gigabyte, that every time there's a problem, you buy more disk. And quite honestly, it's not only about cost per gigabyte. At the end of the day, storage is irrelevant. What you want is work out of it. That's I/O, and that's where solid-state excels. There's also no stone-written rule that you have to have spinning disks anywhere for storage. It could be something entirely different. But, to get those two things understood, people need to stop and think with their head and not with their heart.

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