According to the Register, Dell EMC will be providing PowerMax thanks to its version of storage-class memory (SCM), which is a non-volatile storage tier. It’s faster than flash, but cheaper and not quite up to speed with DRAM. Unlike flash, it can “be addressed by software directly at byte-level with memory (load, store) semantics.”
Intel’s version of SCM is called 3D Xpopint Optane, a technology available as a DC P4800X SSD or DC Persistent Memory NVDIMM. These technologies’ read latencies are 10,000 nanoseconds and 350ns, respectively. DRAM is less than 100ns and an SAS SSD is about 75,000ns.
HPE cut its latency in half in its 3PAR and made it twice as fast than all-flash arrays by adding Octane caching (Memory-Driven Flash) and using NVMe solid state drives. This prompted Dell EMC and Round Rock to contact The Register and update them on their high-end PowerMax array and SCM.
SCM will be directly supported by the PowerMax OS, using a low-latency NVMe-oF link that speeds up a user’s data access. Optane SSDs will be dual-ported and mounted in the Disk or Drive Array Enclosures (DAEs) inside the array, providing data-at-rest encryption.
The dual port is a particularly important feature that is seen as a requirement for enterprise-class storage, as it protects users from single port failures. Each port has its own queue, allowing the PowerMax software to use separate queues for reads and writes, which allows for more IO processing. It can also use different directors for each port, which makes RAID groups more efficient.
Dell EMC is also looking at having PowerMax support another faster their of SCM called Optane DC Persistent Memory (Xpoint DIMMs).
“Most SCM implementations today are cache,” explained Caitlin Gordon, Vice President of Marketing at Dell EMC storage. “We are using it as a persistent tier.”