On June 18th 2020, Intel announced the next generation of 3D XPoint memory under its Optane brand. Named Optane Persistent Memory 200 Series, those modules provide up to 4.5 TB of memory per socket (more on this below).
2nd-Gen Optane consists of four layers of 3D XPoint memory, whereas 1st-Gen had only two layers.
Optane Persistent Memory 200 series are available in modules of 128, 256 and 512 GB. Up to six modules are supported per single CPU socket, providing up to 3 TB of PMEM per socket. When combined with DRAM modules, the maximal memory capacity supported per socket is 4.5 TB (taking into account DRAM and Optane).
Media write endurance information is available on Intel’s Optane Persistent Memory 200 Series Data Sheet, and seems to show that in all write profiles, the 256 GB module seems to offer the highest endurance of all.
From a bandwidth perspective, speeds up to 8.10 GB/s are reached with the 256 GB module for 100% reads, and up to 3.15 GB/s for 100% writes. The Data Sheet has several read/write profiles, which do not state if reads are random or sequential, so it’s safe to assume those are sequential reads.
Those modules deliver faster I/O compared to the 1st-Gen Intel Optane DC Persistent Memory modules. It is not clear yet whether this increase is linked to CPU-side optimizations or whether this is due to improvements on the media side.
Intel states that this product is “compatible with 3rd-Gen Intel Xeon Scalable processors on 4-socket platforms” (those processors were also announced in June 2020).
There are no mentions about whether those modules will be backwards supported or not with 2nd-Gen processors, and whether 2-socket, 3rd-Gen Xeon systems can benefit from them as well.
Understanding Persistent Memory Modes
Intel Optane and 3D XPoint is a technology that we have covered several times at TECHunplugged. What is important to understand is operating modes of 3D XPoint memory when used as persistent memory, notably how Memory Mode and App Direct Mode operate.
To keep this post brief, we invite you to read a comprehensive article on the matter that we created for Amazic a few months ago and which is still relevant to understand the topic.
Business challenges solved
Optane DC Persistent Memory addresses different issues based on the operating mode selected.
In Memory Mode, one of the greatest sales points is increased memory size and higher workload consolidation. This augments the density of VMs on a single host and allows more memory to be allocated to memory-intensive applications, at considerably less cost than DRAM price.
This implies of course a proper design of fault domains to understand and mitigate the impact of a host failure when high VM densities are reached.
Applications that support App Direct Mode are able to directly address (read & write) memory from Optane similarly as they would do with DRAM. This completely changes the relationship applications have to memory and to persistent storage (more on those aspects in the Amazic article we referenced to earlier).
This marks Intel’s second product iteration with Persistent Memory. The tight bond between persistent memory and the CPU architecture, as well as high development costs make it unlikely that any other contender would try to compete with them.
3D XPoint is the result of Intel and Micron past collaboration. Micron did introduce a 2nd-Gen 3D XPoint product (based on their own 2nd-Gen, which was not developed with Intel), but it operates as an NVMe SSD and not as persistent memory, and we haven’t found any public information about plans to deliver PMEM based on 3D XPoint (Micron advocates for NVDIMM instead).
In our view, Optane Persistent Memory is now the main business differentiator that balances in favor of Intel processors in the context of enterprise workloads. This is particularly true for usually business-critical in-memory processing workloads and for memory intensive applications, where more density can be achieved at a better price point.
For as much as we appreciate AMD’s processors, architecture and innovation, not having persistent memory support is a gap that needs to be bridged fast, at least for high-end workloads for the time being. While only a tiny fraction of applications now truly benefit from PMEM, the situation may be completely different in a decade from now.
The final question is whether 2nd-Gen Optane (4-Layer) will also come to Optane DC NVMe SSD drives later this year.