Intel® Optane™ DC persistent memory is a new type of high-capacity memory that can support greater VM and container density per server, and is now in general release with the new, second-generation Intel® Xeon® Scalable processor. IT organizations will likely find that Intel® Optane™ DC persistent memory has a lower TCO than using large amounts of DRAM memory or additional servers. Applications and virtualization environments specifically designed for Intel® Optane™ DC persistent memory can take advantage of its large capacity, but also create innovative new capabilities that improve workload performance, utilization, and infrastructure resilience.
Two Modes, One Technology
Intel® Optane™ DC persistent memory has two modes—Memory Mode and App Direct Mode—described in-depth in this Intel blog. When using Memory Mode, applications and operating systems perceive the DRAM and Intel® Optane™ DC persistent memory as a single large pool of volatile memory, no differently than how DRAM is viewed today. But, Intel® Optane™ DC persistent memory’s affordable capacity frequently makes it more cost-efficient than adding additional DRAM.
Using App Direct Mode, applications and operating systems are explicitly aware of the two types of memory in the platform—DRAM and Intel® Optane™ DC persistent memory—and can directs data reads or writes to the memory resource most suitable to the task. Operations that require lower latency and don’t need permanent storage can be executed on DRAM, and data that needs to be made persistent or structures that are very large can be routed to persistent memory.
App Direct Mode’s Memory Persistence and Control Inspire Innovation
Intel® Optane™ DC persistent memory with App Direct mode gives developers a new way to consider memory and storage. It delivers speed and byte-level control comparable to main memory, as well as data non-volatility traditionally only available in SSDs or hard drives. Virtualization software enabled for App Direct mode will expose the underlying persistent memory to applications designed to take advantage of it running inside the VM. In addition, virtualization vendors can create their own innovative ways to use persistent memory to enable new features.
For example, virtualization software traditionally funnels block storage operations to SSDs or hard drives in the platform. With App Direct mode, the virtualization software can re-direct a VM’s storage operations from disks to persistent memory, cutting access latencies from microseconds to nanoseconds. Using an enabled virtualization environment, this can be done without modifying the VM or application itself.
Permanent data storage in memory is also enabled with App Direct Mode, which can improve system resilience by recording journals and persistent data storage in memory, rather than disk, for faster database restart. At VMworld 2018, Intel discussed the ability to cut database recovery time from 35 minutes to 17 seconds due to data retained in Intel® Optane™ DC persistent memory on a bare metal system, and demonstrated proportional results on a virtualized platform in the Intel booth.
In the future, VM performance can be further improved with even more efficient use of persistent memory as more applications specifically designate which operations are best suited for DRAM or persistent memory, and virtualization software vendors continue to improve memory management for this new environment.
Greater Memory Capacity Enables Higher VM Density
In some cases, the practical limiter of VM density is the platform’s memory capacity. IT organizations have three main options to deal with this issue.
The first option is over-subscription of memory, where the VMs are allocated virtual memory that, when added together, are greater than the total physical memory in the platform. This works until VM contention for physical memory from workload-intensive applications reaches the point that performance degrades to unacceptable levels.
Another option is to add more memory to the platform. However, DRAM prices increase rapidly with DIMM capacity, so this may be untenable from a cost perspective. Finally, the organization can add VM capacity by increasing the number of servers. This can potentially strain rack and floor space, power and cooling, and the department’s overall budget. All of these options are limiting in some manner.
Intel® Optane™ DC persistent memory is available in modules of 128, 256, and 512 gigabytes, significantly larger than today’s volume DRAM DIMMs. Servers can be configured with over 3-terabytes per CPU, enabling more VMs without over-subscription.
At VMworld 2018, VMware, in partnership with Intel and SAS, delivered a blog and session where a prototype version of vSphere, enabled for Intel® Optane™ DC persistent memory, tripled the number of virtualized SAS analytics workloads running on a standard two-socket server with almost no performance degradation.
This greater memory capacity also enables VMs with larger memory footprints, allowing applications in the VM to store more data in memory, rather than disk, which can further improve performance. Proper system configuration and workload behavior are important factors in application performance when using Memory mode, and are discussed in-depth in the companion article in this Gartner newsletter, titled, “Intel® Optane™ DC Persistent Memory – Configuring Platforms for Best Performance.”
Virtualization Leaders Already Enabling for Intel® Optane™ DC Persistent Memory
VMware and Intel have collaborated on persistent memory enabling for over six years, especially in shaping the industrystandard programming framework and optimizing VMware software for App Direct mode. VMware stated that their core virtualization suite, vSphere, will fully support the Intel® Optane™ DC persistent memory feature set at its general availability launch. VMware’s virtualization platform will not only support the greater VM density enabled by large capacity, but also deliver direct access to the persistent memory hardware for virtualized applications that use App Direct mode.
In addition to leveraging overall density improvements, VMware innovations support speed-up of legacy storage workloads by allowing transparent mapping of virtual SCSI devices to persistent memory, and enabling customers to live-migrate VMs across persistent memory types. This last feature will enable customers who invested in expensive, battery-backed NVDIMM-N devices to seamlessly transfer associated VMs to Intel® Optane™ DC persistent memory.
“It’s truly a game-changer,” says Rich Brunner, CTO, Server Platform Technologies at VMware. “App Direct Mode was easier to implement because of the ground work Intel, VMware, and others did to make the programming model ubiquitous before shipping the first product.”
At Microsoft, Erin Chapple, Corporate VP, Windows Server said, “Large, persistent memory has the potential to be one of those rare, truly transformative technologies.”
Microsoft Hyper-V and Storage Spaces Direct in Windows Server 2019* includes native support for Intel® Optane™ DC persistent memory, which will allow larger datasets to be closer to compute, ultimately creating faster databases as larger datasets are stored entirely in memory. Together, the technologies reached an industry-leading HCI benchmark of over 13.7M IOPS. This storage capacity and performance will make hyper-converged infrastructure even more compelling by giving customers the tools to solve larger, more complex business problems.
Intel engineers have optimized Linux* kernel 4.2 or higher for Intel® Optane™ DC
persistent memory support. IT decisionmakers should contact their Linux distributor about their plans to incorporate the technology. More information about persistent memory deployment can be found on the Intel Software Developer Zone.
Coming Together Around Industry Standards
Intel® Optane™ memory modules are physically and electrically compatible with standard DDR4 memory slots. On a newestgeneration Intel® Xeon® Scalable processor-based server, slots can be populated with either DDR4 DRAM DIMMs or Intel® Optane™ DC persistent memory modules.
Intel also paved the way for widespread industry readiness of persistent memory by supporting industry standard persistent memory programming models defined by the Storage and Networking Industry Alliance (SNIA), ACPI, and others. This provided a common software framework for application and virtualization developers that is compatible with all compliant persistent memory.
“It’s not just generic support,” continues VMware’s Rich Brunner. “It’s sophisticated error testing, proving the platform delivers the endurance through power failures, and optimizing application software models, hardware, hypervisor, and more.”
With DRAM-like latency, byte-addressable instructions, and storage-like data persistence, Intel® Optane™ DC persistent memory significantly expands virtualization efficiency and innovation. As applications are created to take advantage of this new memory tier, new services will launch and provide more real-world examples of improved performance and density.
IT organizations looking to increase infrastructure ROI should begin to pilot projects with Intel® Optane™ DC persistent memory in order to see the benefits within their own data centers. Intel encourages organizations to contact their virtualization supplier to find out more about which of their software is ready to take advantage of this new technology.