Optimizing With Intel Optane DC Persistent Memory
Like other Optane-branded products, Optane DC Persistent Memory leverages 3D Xpoint memory technology. If you recall, 3D Xpoint is a non-volatile memory type that behaves like somewhat of a hybrid of DRAM and NAND flash memory. 3D Xpoint offers significantly better performance than NAND flash memory, however, with DRAM-like access times. 3D Xpoint also offers higher endurance than traditional NAND flash memory, but with similar capability to scale in density.
When it was initially announced in partnership with Micron a few years back, Intel claimed that 3D Xpoint was 1000x faster than NAND, with 1000x the endurance, and 10x the density potential of DRAM. Due to its unique properties, 3D Xpoint is well suited to an array of products, in both the storage and memory markets. With Optane DC Persistent memory, Intel is positioning the technology as a new memory tier that bridges the gap between DRAM and high-performance storage.
Optane DC Persistent memory has the potential to drastically disrupt the way Intel’s data center customers handle and manage massive datasets. Keeping large amounts of data closer to the processor, attached via a high-bandwidth / low-latency interconnect, while simultaneously minimizing the need to access the slower storage subsystem, is the key benefit of Optane DC Persistent Memory.
With Optane DC Persistent Memory, multiple terabytes of non-volatile memory can be directly attached to the CPU in conjunction with traditional DRAM, which allows for quicker access to more data. In addition, because it is non-volatile, the need to re-copy large amounts of data back into memory, should a server need to be re-booted for whatever reason, is minimized or eliminated, which can reduce downtime considerably.
Optane DC Persistent memory can be attached to a system in conjunction with traditional DRAM. The amount or ratio of DRAM to Optane DC Persistent memory will vary based on customer needs, but typically there would be significantly more Optane DC Persistent Memory than DRAM, to maximize the overall capacity. It attaches via the very same DDR4 memory slots, but we should point out that it uses different protocols and is managed differently than DRAM, hence the need for Cascade Lake
Requests for data in memory always go through the DRAM first. With Optane DC Persistent Memory, the system’s DRAM is essentially turned into a large cache pool. This reduces overall latency and minimizes writes to the 3D Xpoint memory to maximize endurance. The technology, however, can currently be configured in two ways – Memory Mode or App Direct Mode. In memory mode, the Optane DC Persistent memory exists “above” the DRAM. The DRAM in the system is essentially configured as a cache and the available memory capacity to the system is equal to the amount of Optane DC Persistent memory that is installed. Memory mode is best suited to legacy applications that would benefit from large amounts of available memory.
In App Direct mode, the DRAM and Optane DC Persistent Memory are pooled together to maximize the total capacity. To best leverage this mode, however, workloads have to be optimized for this configuration to balance the latency and bandwidth benefits of DRAM with the persistence and larger capacity of the Optane DC Persistent memory.
Optane DC Persistent Memory will be available in DIMM capacities of 128GB on up to 512GB initially, which will allow for many terabytes to be installed in a single server, in capacities much higher than DRAM alone.