Chances are you have heard a lot of buzz around persistent memory, but are not quite sure what use cases would benefit the most from this new technology.
Persistent Memory can be configured in Memory Mode as a DRAM replacement, in AppDirect Mode as a storage device, or a combination of the two.
SUSE® Linux Enterprise (SLE) has supported AppDirect Mode beginning with SLE 12 SP4. However, since each Persistent Memory mode is configurable in Linux, as a result, SUSE has recently released an official statement supporting each of these modes with SUSE Linux Enterprise. This change is reflected in the updated Release Notes1 for SUSE Linux Enterprise Server 15 SP1 below:
6.1.1 Intel OptaneTM DC Persistent Memory Operating Modes
Intel Optane DC Persistent Memory has two operating modes, AppDirect (storage) mode and Memory Mode.
In Memory Mode, the Optane DIMMs serve as cost-effective DRAM replacement. To applications the Optane memory is presented as volatile memory (that is, not persistent), just like on DRAM-only systems. In reality this is a combination of Optane and DRAM, where DRAM acts as a cache for the most frequently-accessed data, while the Optane persistent memory provides large memory capacity. The setup is slower with random access workloads than on DRAM-only systems, but allows for higher capacity memory and is more cost-effective. In this mode, data is not persistent, which means it is lost when the system is powered off.
Intel Optane running in memory (and mixed) mode is supported with SUSE Linux Enterprise Server running on (YES) certified platforms. Users running applications that take advantage of this mode must understand that without specific enhancements, performance may decrease.
Direct any hardware related questions at your hardware partner. SUSE works with all major hardware vendors to make the use of Intel Optane a perfect user experience on the operating system level and open-source infrastructure level.
In addition, SUSE Linux Enterprise Server 12 SP4 is also now officially supported with Persistent Memory in all memory mode configurations.
With these changes, SUSE IHV partners can now certify with Intel® Optane DC Persistent Memory configured in Memory, AppDirect or Mixed Mode using the YES System Certification2 Kit (SCK) v8.2 or newer.
As mentioned in the release notes, certified platforms will be supported by SUSE. In order to achieve this support, YES Certification requires hardware partners configure and test systems with the corresponding supported mode as outlined below:
AppDirect Mode Only: Configure and test PMEM in AppDirect mode
Memory Mode Only: Configure and test PMEM in Memory mode
All Modes Supported: Configure and test PMEM in Mixed mode
YES Certification bulletin changes
With the addition of Memory and Mixed Mode testing, systems certified with Persistent Memory will now highlight the total memory, supported mode(s) and the number of modules in the Tested Configuration section of the YES Certification Bulletin3.
If the system only supports AppDirect Mode, the bulletin will only list the Tested Configuration amounts (no Config Note).
If the system only supports Memory Mode, the bulletin will contain a Configuration Note stating Memory Mode only.
If the system supports Mixed Mode, the bulletin will also contain the configuration note highlighting this.
See sample bulletin below:
Persistent Memory Use Case
The datacenter used to be all about data backup and storage. Today’s datacenter however, has been taken over by Big Data. It’s no longer enough to be able to access emails and spreadsheets. With the demands of IoT and analytics, you must be able to store unprecedented amounts of data, and analyze that data for a myriad of disparate applications, and do it in real time. Because of this, transactional databases like Oracle have become the center of your business. The industry needed a solution that combined the performance of memory with the persistence of storage. Persistent memory does just that by utilizing non-volatile DRAM for application performance acceleration, with a layer of flash storage that stores the application data.
Longtime SUSE partner, HPE, has shown that Oracle running on SUSE Linux Enterprise greatly improves performance when combined with their Persistent Memory modules. Recent testing4 shows a significant increase in performance when Oracle redo logs were moved from traditional SSD drives to HPE Persistent Memory.
For more information on the HPE/SUSE/Oracle test results, configuring Persistent Memory or using the YES Certification test kit, please refer to the documents linked below:
- SUSE Linux Enterprise 15 SP1 Release Notes
- SUSE YES Certification Kit and Documentation
- SUSE YES Certification Bulletin Search
- HPE Persistent Memory Improves Oracle Performance