Tiered Memory for Virtual Machines

As the data explosion continues, VMs with larger memory capacities are necessary in today’s data centers. But DRAM DIMM capacity is not scaling at the same rate as memory demand, and is not keeping pace with modern high-core-count processors. Not to mention that buying TBs of DRAM can be cost-prohibitive.

For VMware vSphere deployments, the solution is memory tiering. Similar to the well-accepted concept of tiered storage, memory tiering uses affordable large-capacity memory for main volatile system memory, coupled with traditional DRAM used as memory cache. Most virtualized applications and databases are ideal candidates for a tiered memory architecture using DRAM and Intel® Optane™ persistent memory (PMem) because they often consume host memory that is not actively used by the VM.

VMware ESXi or similar environments can experience a wide array of benefits from using tiered memory to expand memory capacities beyond DRAM limitations. Most virtualized, general-purpose workloads—either on-premises or in the hybrid cloud—with low active memory utilization are excellent candidates for a tiered memory structure. Examples of such workloads include virtual desktop infrastructure (VDI) and databases.

Intel® Optane™ PMem offers excellent business value along two primary vectors: increasing VM density (with a lower cost per VM) or saving capital expenditures (CapEx) at the same VM density by right-sizing DRAM and using memory tiering. Intel® Optane™ PMem proof points are available from intel.com.

VMware vSphere (vSphere 6.7 EP10 and later) supports Intel® Optane™ PMem 100 series with 2nd Gen Intel® Xeon® Scalable processors. vSphere 7.0U2 and later supports Intel® Optane™ PMem 200 series with 3rd Gen Intel® Xeon® Scalable processors. Many configurations are supported, and VMware provides several best practices for using Intel® Optane™ PMem with VMware software. For example:

  • The recommended DRAM sizes are as follows:
  • A 1:8 ratio of DRAM to Intel® Optane™ PMem, which is 12.5 percent of Intel® Optane™ PMem capacity.
  • A 1:4 ratio of DRAM to Intel® Optane™ PMem, which is 25 percent of Intel® Optane™ PMem capacity.
  • The system must be populated with at least four Intel® Optane™ PMem DIMMs per socket.
  • Maximum performance is achieved when active memory of the host in steady state fits within the amount of DRAM configured in the host.
  • The server platform should be running with the Balanced Profile BIOS setting recommended by the server OEMs.

At a time when technology trends demand VMs to support ever-larger sizes without sacrificing performance, Intel’s memory breakthrough provides an opportunity to surpass traditional architecture limitations, consolidate server resources, and significantly reduce TCO. Intel® Optane™ PMem is an affordable solution that drops right into existing DDR4 memory slots. IT can right-size DRAM investments and expand total memory per server, accommodate much larger workloads, increase VM density, and dramatically improve resource utilization.

These benefits fit perfectly with enterprises in the midst of their digital transformation. Companies working to modernize their infrastructure and increase their efficiency to meet the mounting wave of data demands can benefit from tiered memory systems that take advantage of Intel® Optane™ PMem.