The Importance of Automated Headroom Management

Before we begin: This is another vendor-neutral post. I realize there may be no architecture that can do everything I’m proposing, but some may come closer to what you need than others. Whether you’re a vendor or a customer, see it as stuff you should be doing or be asking for respectively…

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The Well-Behaved Storage System: Automatic Noisy Neighbor Avoidance

This topic is very near and dear to me, and is one of the big reasons I came over to Nimble Storage.

I’ve always believed that storage systems should behave gracefully and predictably under pressure. Automatically. Even under complex and difficult situations.

It sounds like a simple request and it makes a whole lot of sense, but very few storage systems out there actually behave this way. This creates business challenges and increases risk and OpEx.

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Architecture has long term scalability implications for All Flash Appliances

Recently, many vendors announced the availability of large SSDs. It’s not extremely exciting – it’s just a larger storage medium. Sure, it’s really advanced 3D NAND, it’s fast and ultra-reliable, and will allow some nicely dense configurations at a reduced $/GB. Another day in Enterprise Storage Land.

But, ultimately, that’s how drives roll – they get bigger. And in the case of SSD, the roadmaps seem extremely aggressive regarding capacities, with 100TB per device coming.

Then I realized that several vendors don’t have large SSD capacities available.

But why? Why ignore such a seemingly easy and hugely cost-effective way to increase density?

In this post I will attempt to explain why certain architectural decisions may lead to inflexible design constructs that can have long-term flexibility and scalability ramifications.

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An explanation of IOPS and latency

<I understand this extremely long post is redundant for seasoned storage performance pros – however, these subjects come up so frequently, that I felt compelled to write something. Plus, even the seasoned pros don’t seem to get it sometimes… 🙂 >

IOPS: Possibly the most common measure of storage system performance.

IOPS means Input/Output (operations) Per Second. Seems straightforward. A measure of work vs time (not the same as MB/s, which is actually easier to understand – simply, MegaBytes per Second).

How many of you have seen storage vendors extolling the virtues of their storage by using large IOPS numbers to illustrate a performance advantage?

How many of you decide on storage purchases and base your decisions on those numbers?

However: how many times has a vendor actually specified what they mean when they utter “IOPS”? 🙂

For the impatient, I’ll say this: IOPS numbers by themselves are meaningless and should be treated as such. Without additional metrics such as latency, read vs write % and I/O size (to name a few), an IOPS number is useless.

And now, let’s elaborate… (and, as a refresher regarding the perils of ignoring such things when it comes to sizing, you can always go back here).

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