Olivier Le Moal - stock.adobe.co
Although Gartner's Hype Cycle posits a neat theory for the adoption of a new product category, events often don't play out so cleanly in practice. Some products, like the smartphone, are an instant success. Others, like the Segway, gain less of a following, either because they don't fill a pressing need or people don't know what to do with them. More than five years after its introduction, Optane memory is solidly in the second camp.
Intel marketing has carved out a niche for Optane as a new memory tier between volatile DRAM and slower, non-volatile NAND flash. However, adoption has been slow because of the poor price-performance tradeoff -- primarily a result of plunging NAND prices -- and confusion over how best to use Optane in servers and storage arrays.
Don't blame product designers for being puzzled because there are several different ways to access Optane memory, including storage using SATA or NVMe interfaces and persistent memory DIMMS.
Both Optane persistent memory (PMem) and SSDs use the same memory chips but are packaged for different I/O interfaces: the DRAM bus for PMem and SATA or NVMe interface for SSDs. Most array implementations use Optane drives in a standard SATA or NVMe slot and as a caching layer to buffer SSDs or HDDs. However, software-defined storage products that can use industry-standard servers as storage nodes can theoretically use banks of PMem to supplement conventional SSDs in a scale-out storage node. Note that a 16-socket motherboard could scale up to 6 TB of PMem and still leave four sockets for system DRAM.
Storage vendors finally embraced Optane in 2020 as Intel reiterated its commitment to the technology by releasing products, including a new hybrid category that combines Optane and QLC NAND. Although it targets PCs, the category could inspire future Optane-ready enterprise products. The availability of third-generation Optane components coincided with the introduction of several enterprise arrays that support Optane as a distinct storage tier aside from conventional SSDs.
A sampling of Optane-ready storage products
Optane SSDs are easy substitutes for standard NAND flash drives in storage arrays. However, significant software updates are required to make the most out of their higher performance. Still, the software modifications are a secondary impediment to adoption compared with the significant cost difference. For example, a 480 GB Intel U.2 drive runs $620 ($1.29 per GB) compared with $540 for a 3.8 TB ($0.14 per GB) TLC enterprise SSD, which makes Optane nine times more expensive per gigabyte.
StorOne, one of the first companies to use Optane as a discrete storage tier, justifies Optane's cost in its limit of the number of drives per array and use of optimizing software to automatically place hot, I/O-intensive workloads on the Optane tier. It also notes the cost and wasted capacity when duplicating such high IOPS by using wide arrays of SSDs in parallel.
Cost notwithstanding, several vendors support Optane as either a discrete storage tier or in-memory cache. Optane-ready products include:
- Dell EMC PowerMax array
- Formulus Black Forsa
- HPE 3PAR StoreServ 9000 Storage
- HPE Nimble Storage All Flash Arrays
- SmartX Halo P series appliance
- StorOne All-Flash Array.next
- Vast Data Universal Storage
For more technical details on these products, see the table below.
Self-managed hardware isn't the only way to use Optane to accelerate storage performance. Azure offers SAP HANA Large Instances with Optane PMem in App Direct Mode to extend DRAM and create massive persistent in-memory databases. HANA supports App Direct Mode to load as much of a database as possible into Optane. Unlike DRAM in-memory instances, data survives an instance reboot. Oracle also supports PMem in App Direct and offers an Exadata X8M cloud instance using PMem.
Optane isn't the only option for high-performance non-volatile memory. Both the Samsung Z-SSD and the Toshiba XL-Flash bridge the performance gap between Optane and TLC/QLC flash by using SLC cells with larger DRAM caches and high-performance controllers. Samsung's SZ985 NVMe drive promises 3 GBps sequential read and write throughput with latency less than 0.15ms in PCIe cards with up to 3.2 TB capacity. Samsung claims that the drive hits 750,000 random read IOPS, 88% faster than its enterprise SSD counterpart.