In this era of over-marketing and misinformation, it can be refreshing to clarify things for customers.
Allow me to be refreshing regarding NVMe 🙂
NVMe is simply a protocol. Just like SCSI is a protocol. NVMe is most assuredly not a media type. Yet, storage vendors keep talking about “NVMe drives” and customers often think those devices are equal as long as “NVMe” is mentioned.
Alas, that’s not how things work…
Strictly speaking, there’s no such thing as an NVMe drive. Or, at the very least, calling something an “NVMe drive” isn’t enough to describe what that media is, and it’s especially not enough to describe how fast it may be.
Continue reading “Media is Not Created Equal and NVMe is Just a Protocol”
Just a quick post to address something many people either get wrong or just live with due to convenience.
In summary: Please, let’s stop using average I/O sizes to characterize storage system performance. It’s wrong and doesn’t describe how the real world works. Using an average number is as bad as using small block 100% read numbers shown in vanity benchmarks. Neither is representative of real life.
Using a single I/O size for benchmarking became a practice for a vanity benchmark and to provide a level playing field to compare multiple products.
But, ultimately, even though the goal of comparing different systems is desirable, using a single I/O size is fundamentally flawed.
Continue reading “Why it is Incorrect to use Average Block Size for Storage Performance Benchmarking”
Before we begin, something needs to be clear: Although dual-ported NVMe drives are not yet cost effective, the architecture of Nimble Storage is NVMe-ready today. And always remember that in order to get good benefits from NVMe, one needs to implement it all the way from the client. Doing NVMe only at the array isn’t as effective.
Continue reading “Practical Considerations for Implementing NVMe Storage”
<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 RAID type, randomness, 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).
Continue reading “An explanation of IOPS and latency”