As the best cloud service for traditional applications, we are continually working to enhance features and functionality, especially for our IBM Power users. In the past few months, we’ve released a number of improved to help customers be more efficient with how they consume IBM Power in Skytap. Let’s take a peek at what’s new:
Entitled Capacity Improvements
This change will simplify LPAR configuration, provide better resource predictability, and increase the maximum supported entitled capacity.
What is changing?
- Entitled Capacity will be determined strictly by the amount of RAM based on this formula. EC = GBRAM/40.
- Maximum available Entitled Capacity for AIX/Linux partitions increase to 12.80.
- Maximum for IBM i increases to 4.00 or 60,000 CPWs (this is an IBM restriction based on the P10 processor group).
- Peak workload demand in the Uncapped sharing mode is controlled through the use of the vCPU setting. The minimum allowed setting is equal to GB-RAM, the maximum setting is 16 vCPUs.
- For better control over software licensing, customers can limit entitled capacity by selecting fewer vCPUs, which lowers the number of cores that need to be licensed for certain types of software, usually in the case of 3rd party software licenses.
Here are some example configurations:
| Size | GB-RAM | Entitled Capacity | vCPUs |
| Small | 4 | 0.10 | 4 |
| Medium | 32 | 0.80 | 16 |
| Large | 256 | 6.40 | 16 |
| Max AIX/Linux | 512 | 12.80 | 16 |
| Max IBM i | 512 | 4.00 | 4 |
Capped and Uncapped Sharing Modes
AIX and Linux partitions can be configured to run in Uncapped or Capped sharing modes. This is useful for limiting compute resources for software licensing reasons.
- Capped mode doesn’t allow the partition to exceed the assigned entitled capacity even if there are free resources in the processor pool.
- Uncapped mode will let the logical partition to get more processing units if needed if enough resources are available.
When reporting software license usage to certain ISVs like Oracle, the total possible entitled capacity is used to calculate license usage. For instance, if the LPAR is set to 2.0 entitled capacity, but CPU is set to 8, that means that in an uncapped sharing mode, the LPAR will be allocated 2 cores of processing power but have the ability to scale up to 8 cores if there is space available. This is taken care of automatically by the Hypervisor.
Unfortunately for licensing reasons, customers will have to report eight core licenses to ISVs even though the LPAR might not be consuming that amount. In order to rectify this, customers can change the sharing mode to Capped which restricts the Hypervisor from allocating more cores to the LPAR. By doing so, customers can report just two cores of usage to the ISV.
IBM i partitions will always be configured as Capped.
Entitled Capacity Override
For more fine-grained control, customers can override the calculated entitled capacity by typing in the actual entitled capacity values directly through the UI. The limits of the override values will be determined by the GBRAM and CPU settings from the above. Skytap will remember and honor the overridden entitled capacity values and provision the LPAR with that capacity.
These are just the few IBM Power features that we’ve been working on with more to come in the following months. If you have any feedback or ideas for improvement, you can submit them to our Support team through this link: https://www.skytap.com/customer-success/support/
