HMC & CMC

Power Enterprise Pool Primer

By STEPHANIE JENSEN posted Tue June 23, 2020 06:53 PM

  

Power Enterprise Pools (PEP) provides the ability to move processor and memory resources from one server to another any time, with no physical movement of hardware, using easy operator commands in HMC.  The PEP topology is a set of servers that is entitled to share a set of hardware processor and memory licenses between them.  The grouping of this Pool of servers is managed at the HMC level; individual servers do not require any special modifications.  This grouping and sharing allows for fast workload balancing and LPM activity while keeping overall server capital costs lower.  One does not have to purchase licenses for all resources on all systems, but instead can purchase fewer licenses overall and move them when needed, to and from servers as their workload requirements rise and fall.

With HMC V8R8.4.0 or earlier, all PEP servers in a pool must be on one network and managed by one HMC (and its redundant partner). With HMC V8R8.5.0 or later, PEP servers in a pool can be on different networks and managed by multiple HMCs.  See the Power Enterprise Pools - Multiple HMC Support blog for more information. 

Figure 1:   High-level PEP Architecture


An additional advantage of PEP use is seen in LPM (Logical Partition Mobility) scenarios. Suppose you wish to move a partition from Server 1 to Server 3, perhaps to clear work from Server 1 for Maintenance or to consolidate work to only one server. Mobile (Pool) Resources supporting the partition on Server 1 can be removed from Server 1 and assigned to Server 3 to eventually support the partition when it runs on Server 3.  However, until the LPM operation completes, the partition needs those resources ALSO on Server 1. PEP allows for temporary “Persistence” of the resources on BOTH servers while the operations complete.  This allows the client to briefly use more resources than are truly entitled for use in the Pool. This leverages the extra unlicensed resources in place, while preserving the savings of not having purchased all the hardware licenses for full-time use. 

Figure 2:   PEP use to support LPM

Acquiring Power Enterprise Pool capability

Once a deployment of servers that meets (or will meet) the prerequisite requirements exists (or will exist), the client can work with IBM to establish the list of servers that will be participants in the Pool. The number of processors and GB of memory to be shared among the Pool members is ordered by the client, and IBM generates an XML file to be processed by the client's HMC. The HMC reads this XML file and  contacts each server to notify it that it is a Pool member. The HMC also gets the total number of Processors and GB of Memory, permitted for distribution to Pool members, securely from the XML file.

Managing Power Enterprise Pool resources

With a successful PEP setup, the client can use either the HMC GUI facilities or the HMC Command Line Interface to push Pool resources (processors or memory) to server Pool members that have unlicensed resources, and to pull any amount of Pool resources away from a server Pool member to be re-deployed elsewhere. Additionally, the HMC provides REST APIs as another mechanism with which to manage PEP resources.

Figure 3:   HMC GUI showing Power Enterprise Pools top-level interface

 

Power Enterprise Pools - Common Questions

Do I ever have to contact IBM regarding any resource movements?

No. Once you purchase the PEP Resources and configuration file and apply it, the resources are yours to move wherever you wish among the Pool servers.

Are the Pool resources temporary in any way?

No. You own the use of X Number of processor and memory resources, and they are permanently yours. Additionally, once you assign any Pool resources to a server, those resources stay with the server indefinitely, as long as the server remains associated with the HMCs. At server IPL, the HMC must re-validate that the server is entitled to those Pool resources, but beyond that, they stay with the server until YOU move them somewhere else.

Is there any limitation on the type of use of the Pool resource on the server?

No, the Mobile (Pool) processors or memory given to a server are equivalent to any other processor or memory on the server. These Mobile resources can be used in any way any other resource can be used on that system.

More Information?

For more information about multiple HMC support, see the Power Enterprise Pools - Multiple HMC Support blog.

For more information related to Power Enterprise Pools, travel to this link: http://public.dhe.ibm.com/systems/power/docs/hw/p8/p8ha2.pdf  and go to the Power Enterprise Pools section.

Last updated: June 22, 2016

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