Apache Pass

Intel’s Optane: Two Confusing Modes. Part 2) Memory Mode

Exploding HeadThis post is the second part of a four part series in The SSD Guy blog to help explain Intel’s two recently-announced modes of accessing its Optane DIMM, formally known as the “Intel Optane DC Persistent Memory.”

Memory Mode

The most difficult thing to understand about the Intel Optane DC Persistent Memory when used in Memory Mode is that it is not persistent.  Go back and read that again, because it didn’t make any sense the first time you read it.  It didn’t make any sense the second time either, did it?

Don’t worry.  This is not really important.  The difficulty stems from Intel’s marketing decision to call Optane DIMMs by the name “Intel Optane DC Persistent Memory.”  Had they simply called them “Optane DIMMs” like everyone expected them to then there would have been Continue reading

Intel’s Optane: Two Confusing Modes. Part 1) Overview

Exploding HeadIntel recently announced two operating modes for the company’s new Optane DIMMs, formally known as “Intel Optane DC Persistent Memory.”  The company has been trying to help the world to understand these two new operating modes but they are still pretty baffling to most of the people The SSD Guy speaks to.  Some say that the concepts make their heads want to explode!

How does Optane’s “Memory Mode” work?  How does “App Direct” Mode work?  In this four-part series will try to provide some answers.

Like all of my NVDIMM-related posts, this series challenges me with the question: “Should it be published in The SSD Guy, or in The Memory Guy?”  This is a point of endless confusion for me, since NVDIMM and Intel’s Optane blur the lines between Memory and Storage.  I have elected to post this in The SSD Guy with the hope that it will be found by readers who want to understand Optane for its storage capabilities.

Memory Mode is the easy sell for the short term.  It works with all current application software without modification.  It just makes it look like you have a TON of DRAM.

App Direct Mode is really cool if Continue reading

What is SNIA’s Persistent Memory Programming Model?

SNIA Persitent Memory Summit LogoIn this post The SSD Guy will discuss the SNIA Nonvolatile Memory (NVM) Programming Model, a framework to allow standard applications to take advantage of nonvolatile, or persistent, memory in any system that includes persistent memory,

This model is enormously important to the future of computing, yet few people even know that it exists.  It’s a fundamental change to the way that application programs access storage that will have significant ramifications to computer architecture and performance over the long term.

Here’s why: The industry is moving towards larger-scale systems that mix persistent memory with standard DRAM into a single memory address space.  Persistent memory has an advantage over volatile DRAM, since it maintains data after power is removed or lost.  Because of this certain application programs will want to know which memory is volatile and which is persistent and to take advantage of whatever persistent memory the system might provide.  I say “Larger-Scale” systems because small systems often combine Continue reading

Comparing Wear Figures on SSDs

DWPD TBW GB/Day TriangleI have been receiving questions lately from people who are puzzled when companies use different parameters than their competitors use to specify the endurance of their SSDs.  How do you compare one against the other?  Some companies even switch from one parameter to another to define the endurance of different SSDs within their product line.

I have found that Intel uses three different endurance measures for its products: DWPD (drive writes per day), TBW (terabytes written), and GB/day.

There’s not any real difference between any of these measures – each one is one way of stating how many times each of the SSD’s locations can be overwritten before the drive has gone past its warrantied life.

The relationships between these three measures are illustrated in this post’s graphic.  You can click on it to see an expanded version.  It’s all pretty simple.  We’ll spell out the relationships in detail below, but in brief, if you want to compare Continue reading

3D XPoint Memory at the Storage Developer’s Conference

3D XPoint Report GraphicThis Sunday (Sept. 20, 2015) I will be presenting my company’s findings on the 3D XPoint memory that was introduced by Intel and Micron in July.  I will be speaking at the Storage Networking Industry Association (SNIA) Storage Developer Conference (SDC) Pre-Conference Primer.  You can click the name  to be taken to the agenda.

This won’t be the only talk about persistent memory technology at the conference.  Prior to my presentation storage consultants Tom Coughlin and Ed Grochowski will give an overview of advances in nonvolatile memories, and following my presentation will be two Intel talks.

Intel will be covering this new technology a lot during the conference.  Of a total of 120 presentations at the conference and pre-conference primer, Intel will be presenting nine, seven of which directly name persistent memory or nonvolatile memory in the title.  Other firms will also be talking about NVM: AgigA, Calypso, HP, Pure Storage, and SMART Modular.  Even Microsoft alludes to it in a couple of its presentation titles.  Persistent memory is a hot issue.

So, the question for readers of The SSD Guy blog is: “Will this do away with SSDs?”

This is a question that was Continue reading