Blog Posts

Intel Optane Persistent Memory Modules report "Non-functional" state in ipmctl

Issue

Executing ipmctl show-dimm to get device information shows the persistent memory modules in a ‘Non-functional’ health state, eg:

# ipmctl show -dimm

 DimmID | Capacity | HealthState    | ActionRequired | LockState | FWVersion
=============================================================================
 0x0001 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x0011 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x0021 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x0101 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x0111 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x0121 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x1001 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x1011 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x1021 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x1101 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x1111 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A
 0x1121 | 0.0 GiB  | Non-functional | N/A            | N/A       | N/A

Other ipmctl commands may fail and return “No functional DIMMs in the system.”, eg:

How To Set Linux CPU Scaling Governor to Max Performance

The majority of modern processors are capable of operating in a number of different clock frequency and voltage configurations, often referred to as Operating Performance Points or P-states (in ACPI terminology). As a rule, the higher the clock frequency and the higher the voltage, the more instructions can be retired by the CPU over a unit of time, but also the higher the clock frequency and the higher the voltage, the more energy is consumed over a unit of time (or the more power is drawn) by the CPU in the given P-state. Therefore there is a natural trade-off between the CPU capacity (the number of instructions that can be executed over a unit of time) and the power drawn by the CPU.

How To Verify Linux Kernel Support for Persistent Memory

Linux Kernel support for persistent memory was first delivered in version 4.0 of the mainline kernel, however, it was not enabled by default until version 4.2.

If you use a Linux distribution that uses kernel 4.2 or later, or the distro backports features in to an older kernel, you will almost certainly have persistent memory support enabled by default. It is still worth verifying what features are enabled and disabled as this may vary by distro and release version for the very latest persistent memory features.

A Quick Guide to Signing Your Git Commits

It is important to sign Git commits for your source code to avoid the code being compromised and to confirm to the repository gatekeeper that you are who you say you are. Signing guarantees that my code is my work, it is my copyright and nobody else can fake it. This guide provides the necessary steps to creating private & public keys so you can sign your Git commits.

On Linux or Mac, if you have setup a development environment then you have all the necessary tools for signing.

Programming Persistent Memory: A Comprehensive Guide for Developers Book

After many months of hard work by everyone involved, I’m very pleased to announce that the book “Programming Persistent Memory: A Comprehensive Guide for Developers” is now available for download in digital PDF & ePUB formats from https://pmem.io/book , and Kindle & paperback through Amazon .

Beginner and experienced programmers will use this comprehensive guide to persistent memory programming. You will understand how persistent memory brings together several new software/hardware requirements, and offers great promise for better performance and faster application startup times―a huge leap forward in byte-addressable capacity compared with current DRAM offerings.
This revolutionary new technology gives applications significant performance and capacity improvements over existing technologies. It requires a new way of thinking and developing, which makes this highly disruptive to the IT/computing industry. The full spectrum of industry sectors that will benefit from this technology include, but are not limited to, in-memory and traditional databases, AI, analytics, HPC, virtualization, and big data.
Programming Persistent Memory describes the technology and why it is exciting the industry. It covers the operating system and hardware requirements as well as how to create development environments using emulated or real persistent memory hardware. The book explains fundamental concepts; provides an introduction to persistent memory programming APIs for C, C++, JavaScript, and other languages; discusses RMDA with persistent memory; reviews security features; and presents many examples. Source code and examples that you can run on your own systems are included.
What You’ll Learn
- Understand what persistent memory is, what it does, and the value it brings to the industry
- Become familiar with the operating system and hardware requirements to use persistent memory
- Know the fundamentals of persistent memory programming: why it is different from current programming methods, and what developers need to keep in mind when programming for persistence
- Look at persistent memory application development by example using the Persistent Memory Development Kit (PMDK)
- Design and optimize data structures for persistent memory
- Study how real-world applications are modified to leverage persistent memory
- Utilize the tools available for persistent memory programming, application performance profiling, and debugging
Who This Book Is For
C, C++, Java, and Python developers, but will also be useful to software, cloud, and hardware architects across a broad spectrum of sectors, including cloud service providers, independent software vendors, high performance compute, artificial intelligence, data analytics, big data, etc.
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How To Extend Volatile System Memory (RAM) using Persistent Memory on Linux

Intel(R) Optane(TM) Persistent Memory delivers a unique combination of affordable large capacity and support for data persistence. Electrically compatible with DDR4, large capacity modules up to 512GB each can be installed in compatible servers alongside DDR on the memory bus.

Intel’s persistent memory product can be provisioned in a volatile “Memory Mode” which replaces DRAM volatile capacity with the persistent memory capacity, and persistent “AppDirect” mode which presents both DRAM and persistent memory to the operating system and applications. Both modes are explained in more detail here . It is possible to configure a system to utilize a percentage of persistent memory as volatile and persistent, but this mixed-mode still provisions all the DRAM capacity as a Last-Level Cache.

Using Linux Volume Manager (LVM) with Persistent Memory

In this article, we show how to use the Linux Volume Manager (LVM) to create concatenated, striped, and mirrored logical volumes using persistent memory modules as the backing storage device. Specifically, we will be using the Intel® Optane™ Persistent Memory Modules on a two socket system with Intel® Cascade Lake Xeon® CPUs, also referred to as 2nd Generation Intel® Xeon® Scalable Processors.

Linux Volume Manager
When Should You Use LVM with Persistent Memory?
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How to Create a Bootable Windows USB in Fedora Linux

In this tutorial, I am going to show you how to create a Windows Server 2019 bootable USB in Linux, though any Windows version will work. I am using Fedora 30 for this tutorial but the steps should be valid for other Linux distributions as well.

Here’s what you need:

Windows Server 2019 ISO (or Windows 10 ISO)
WoeUSB Application
A USB key (pen drive or stick) with at least 6 Gb of space
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