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PowerVM Capability Offers Value to SAP HANA

A new PowerVM capability called Virtual Persistent Memory (vPMEM) provides a fast restart of workloads during outages in SAP HANA environments.

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Jay Kruemcke recently examined a new PowerVM capability called Virtual Persistent Memory (excerpt below):

“One of the drawbacks of in-memory databases is the amount of time required to load the data from disk into memory after a restart. In one test with an 8TB data file representing 16TB database, it took only six minutes to shut down SAP HANA, but took over 40 minutes to completely load that database back into memory. Although the system was up and responsive much more quickly, it took a long time for all data to be staged back into memory....

“In October 2019, IBM announced Virtual Persistent Memory (vPMEM) with PowerVM. Virtual Persistent Memory isn’t a new type of physical memory but is a way to use the PowerVM hypervisor to create persistent memory volumes out of the DRAM that is already installed on the system. vPMEM is included at no additional charge with PowerVM.

“The data in memory is persistent as long as the physical Power server is not powered off. By maintaining data persistence across application and partition restarts, it allows customers to leverage fast restart of a workload using persistent memory. An added benefit is that there is no difference in application performance when using vPMEM because the underlying DRAM technology is the same as for the non-persistent
memory.

“Although vPMEM does not preserve memory across a server power down, most IBM Power customers seldom power off their systems because of the many reliability features that are built into Power hardware. vPMEM provides for fast restart in the vast majority of planned maintenance and unplanned outages without compromising the performance of HANA during normal use.”

The excerpt below comes from IBM's Asim Khan, program director, offering management for SAP HANA on POWER:

"The feedback we received from our HANA on POWER clients was that Power Systems clients do not face the challenge of frequent hardware-related outages. In fact, one large SAP HANA client told us they haven’t had to reboot their Power System for 30 months straight due to any hardware outages. The Forrester TEI Study of IBM Power Systems for SAP HANA determined an average reduction of 48 hours of annual downtime after customers move from non-POWER environment to Power Systems. What POWER clients say they want is a solution that helps to fast restart the environment when there’s a software-related planned (patch the OS or SAP environment) or unplanned outage in their SAP HANA environment."

As you evaluate SAP HANA, hopefully this technology factors into your decision-making calculus. And if you want to get deeper into vPMEM, check out this IBM Techdocs Library whitepaper by Jim Nugen and Olaf Rutz. Related docs are also available.
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