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Persistent Memory Enhancements : Delivering Persistence Without Compromising Performance

 Asim Mustafa Khan discusses IBM's commitment to Persistent Memory Enhancements.

This blog is part of the strategy that discusses the memory enhancements on IBM Power Systems for SAP HANA. 

IBM has introduced a new capability called Virtual Persistent Memory (PMEM) in the virtualization platform (IBM PowerVM) of IBM Power Systems.  This will address the following business requirements that clients have shared with us:

  • Clients demand choice, and all x86 vendors who are embracing a single persistence technology from Intel are, in essence, the same proprietary technology.

  • Our current SAP HANA on IBM Power clients do not have nearly as many server outages, but even they would like to be able to restart faster after patching their software stack.

  • Clients (on x86 or Power) do not want to tradeoff performance for persistence.

  • Clients want to add the persistent memory capability without having to rip and replace or purchase expensive add-ons to hardware they just recently bought.

IBM Virtual Persistent Memory is an enhancement in PowerVM that introduces the ability to configure persistent volumes using the existing DRAM technology. This is being made available on existing POWER9 processor-based systems with just a firmware upgrade and that too at no additional costs. There are no additional HW components or memory modules required on Power Systems with this solution, this functionality is added on top of the standard memory DIMMs that are available on IBM Power Systems.

Persistence Without Compromising Performance, Virtualization and TCO

Since this feature is based on existing DRAM technologies, it has the same performance characteristics clients already experience today, providing clients with the peace of mind of using technology that already meets their performance requirements. 
You may be wondering why we think that persistence at the LPAR level is the best solution.  We could have aimed to match what the x86 competition was planning, but the loud feedback we received from our existing HANA on Power clients was: “Why try to solve a problem you don’t have?”

Data stored in Virtual Persistent Memory remains persistent as long as the PowerVM hypervisor stays operational. The data is NOT erased by a restart of the application accessing them, nor by a Linux OS (i.e. LPAR) reboot. Thus, data stored in Virtual PMEM stays operational in majority of the typical downtimes.



Clients who had lots of experience with x86 and POWER for SAP HANA told us that, when they switched to POWER, hardware related outages became very rare (unlike when HANA is running on x86 based servers).  When using POWER, the vast majority (if not all) of the outages that the clients have are for operational needs like OS or application related upgrades and patching. And they needed to reduce this maintenance window to improve availability of the environment to their businesses without the fear of degrading everyday performance. Our PowerVM with PMEM solution meets and in fact exceeds all these requirements. 

Advantages of Virtual Persistent Memory

The new enhancement of Virtual Persistent Memory on IBM Power Systems for SAP HANA workload, provides significant benefits to the clients in comparison to competitive persistent memory related solution offerings and some of the important ones are mentioned below: 

  • This solution helps the customer in not only improve SAP HANA restart time but also help reduce the shutdown time thus resulting in significantly reduced maintenance related outage of SAP HANA environment, which further maximizes the uptime of SAP HANA environment for business. 
  • This persistency-based solution is built on DRAM. As a result, it preserves the runtime performance, unlike the competitive offering where the latency gets introduced with their HW technology which is slower than DRAM based memory. Also, this solution provides better memory affinity and NUMA awareness, resulting in SAP HANA clients not only getting persistency but also continue to get faster insights. 
  • This solution is based on virtualization. Hence clients will continue to have the ability to have multiple VMs running on a single system and capability to change persistent memory allocation on demand that will help the customers in providing much more improved flexibility. Whereas the competitive solution for persistent memory is still not certified by SAP to be used with virtualization. Hence the deployments will continue to be bare metal which will have a negative impact on the Total cost of ownership of the environment.
  • No new special Hardware is required. As all this functionality is built on top of existing DRAM technology available on IBM Power systems and can be seamlessly shared and reused by SAP HANA and other applications.
  • Unlike x86 vendors, we won’t force our existing SAP HANA on POWER9 clients to rip and replace their recently procured hardware and pay to have this feature. It will be available to all clients running POWER9 processor-based servers with a simple software update at no additional cost!

The information mentioned regarding potential future products is not a commitment, promise, or legal obligation to deliver any material, code or functionality. Information about potential future products may not be incorporated into any contract. The development, release, and timing of any future features or functionality described for our products remains at our sole discretion. Performance is based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput or performance that any user will experience will vary depending upon many factors, including considerations such as the amount of multiprogramming in the user’s job stream, the I/O configuration, the storage configuration, and the workload processed. Therefore, no assurance can be given that an individual user will achieve results similar to those stated here.


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