Virtual Persistent Memory Benefits on IBM Power Systems

[asimk01]

Earlier this year SAP released the support statement of Virtual Persistent Memory on IBM Power Systems for SAP HANA workloads (SAP Note 2188482), we have already seen some very useful informational blogs that have been posted in the SAP Blogs community by uwe.heinz1 on the introduction of the persistent memory technology, denys.kempen on SAP HANA on IBM Power Systems success story and dennis.padia posted more detailed blogs on how to implement this technology and comparison of the technology with Intel’s Optane. In this blog my objective is to help the team understand how the clients have started to take the benefit of this technology on IBM Power Systems.

Virtual Persistent Memory - is basically an enhancement in advanced Virtualization platform (PowerVM) available only on IBM Power Systems for SAP HANA that introduces the ability to configure persistent volumes using the existing DRAM available on the system. This technology is made available on POWER9 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 because this functionality is added on top of the standard memory DIMMs that are available on IBM Power Systems.

There are several benefits that that clients have seen with the adoption of Virtual Persistent Memory on IBM Power Systems and some of the major ones are mentioned below:

a. Maximize the Uptime of SAP HANA Environment:

Faster Restart:

We have heard it from our clients that they do not have a challenge from HW failure perspective on IBM Power Systems and our clients have suggested that for all the HANA and OS related planned and unplanned maintenance work, they needed a solution that will assist them in restarting the environment faster.

With the Virtual Persistent Memory solution the clients now have the ability to add  persistency layer on their existing memory (DRAM), that allows them to restart their environments by ~17X (based on IBM Internal testing) faster in case of any planned or unplanned maintenance work like HANA related patching, upgrades, OS related patching, upgrades or unplanned outages related to HANA or OS.

Faster Shutdown:

This is also very important aspect from maintenance window perspective as the clients need to bring down the environments fast and perform the maintenance work and then restart the environments as fast as possible to reduce the business impact. On POWER platform when the Virtual persistent memory solution is used, this shutdown time also decreases.

The Clients are seeing the benefits in different ways, one set of clients told us that it has helped them in being able to do more in the change control outage window as less amount of time is spent on stop and restart of the environment, whereas another set of clients told us that they are requesting for a smaller outage window from the business compared to what they were asking earlier, but both the scenarios show that this technology results in the ability to maximize their uptime even further and help exceed their availability related KPIs.

b. Continue to get faster insights

On Power Systems, since Virtual PMEM solution is based on DRAM technology thus it has helped our client to preserve the same runtime performance that they are familiar with while using DRAM, thus even with persistence layer, the clients are able to get significantly faster insights and not have to choose between performance and adding persistence layer (unlike on the persistent memory solutions available on other HW technology). Also an important thing to highlight is that Virtual Persistent Memory is the only persistence based solution available that is NUMA aware meaning it is able to provide better performance than any other persistent memory solution for SAP HANA workload currently available in the market.

Since Virtual PMEM is not a HW based persistent memory solution thus there is no additional encryption needed from HW perspective that means it continues to help in preserving the same run time performance that the clients are familiar with while using HANA on their current DRAM based technology, meaning Virtual PMEM solution is providing persistency in the memory without adding any latency to the environment.

c. Improved Flexibility

For years PowerVM Virtualization on POWER platform has been a key differentiator to our SAP HANA clients, as it provides an unmatched flexibility in the industry and the best thing for SAP HANA clients is that Virtual PMEM is supported with Virtualization that means the clients continue to use virtualization and carve out VMs as per their business needs, helping the clients to build and continue getting the flexibility that they have become familiar with helping them improve their Total Cost of ownership of their environment and not limiting them to HW based limitations.

Another flexibility is the simplification of the deployment model, since this technology is based on the same DRAM based technology that means there are NO specific DRAM:persistent memory ratios (that needs to be followed depending on the workload type) that the clients need to adhere to while ordering and configuring the HW and we have heard this feedback from our partners and clients that this really simplifies the deployment model.

Also from the future growth perspective, if the client wants to redefine the persistent memory limits, they can do these changes using Virtual PMEM solution on POWER on demand, without having to buy new Hardware this helps the clients in making the changes and are not bound or limited because of the HW limitation.

In the end, I just want to say is that the introduction of this technology has helped the clients decision making process more simpler to deploy persistent memory in their SAP HANA environment, as Virtual Persistent Memory on IBM Power Systems provides a persistent memory solution without any compromise on performance and resiliency, along with the virtualization support and all of this is made available to clients using IBM POWER9 systems for FREE!

Please review the following Configuration and Scripting document (LINK) available in IBM Techdocs that explains the technology in more detail and how to set it up for SAP HANA workloads. Hope the team will find this information useful and for questions or clarifications please do not hesitate in reaching out to me.