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Tag Archives: persistent memory

DRS Enhancements in vSphere 6.7

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A new paper describes the DRS enhancements in vSphere 6.7, which include new initial placement, host maintenance mode enhancements, DRS support for non-volatile memory (NVM), and enhanced resource pool reservations.

Resource pool and VM entitlements—old and new models

A summary of the improvements follows:

  • DRS in vSphere 6.7 can now take advantage of the much faster placement and more accurate recommendations for all DRS configurations. vSphere 6.5 did not include support for some configurations like VMs that had fault tolerance (FT) enabled, among others.
  • Starting with vSphere 6.7, DRS uses the new initial placement algorithm to come up with the recommended list of hosts to be placed in maintenance mode. Further, when evacuating the hosts, DRS uses the new initial placement algorithm to find new destination hosts for outgoing VMs.
  • DRS in vSphere 6.7 can handle VMs running on next generation persistent memory devices, also known as Non-Volatile Memory (NVM) devices.
  • There is a new two-pass algorithm that allocates a resource pool’s resource reservation
    to its children (also known as divvying).

For more information about all of these updates, see DRS Enhancements in vSphere 6.7.

Persistent Memory Performance in vSphere 6.7

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We published a paper that shows how VMware is helping advance PMEM technology by driving the virtualization enhancements in vSphere 6.7. The paper gives a detailed performance analysis of using PMEM technology on vSphere using various workloads and scenarios.

These are the key points that we cover in this white paper:

  • We explain how PMEM can be configured and used in a vSphere environment.
  • We show how applications with different characteristics can take advantage of PMEM in vSphere. Below are some of the use-cases:
    • How PMEM device limits can be achieved under vSphere with little to no overhead of virtualization. We show virtual-to-native ratio along with raw bandwidth and latency numbers from fio, an I/O microbenchmark.
    • How traditional relational databases like Oracle can benefit from using PMEM in vSphere.
    • How scaling-out VMs in vSphere can benefit from PMEM. We used Sysbench with MySQL to show such benefits.
    • How modifying applications (PMEM-aware) can get the best performance out of PMEM. We show performance data from such applications, e.g., an OLTP database like SQL Server and an in-memory database like Redis.
    • Using vMotion to migrate VMs with PMEM which is a host-local device just like NVMe SSDs. We also characterize in detail, vMotion performance of VMs with PMEM.
  • We outline some best practices on how to get the most out of PMEM in vSphere.

Read the full paper here.