Fixes are available
8.5.5.1: WebSphere Application Server V8.5.5 Fix Pack 1
IBM WebSphere Virtual Enterprise Version 7.0 Fix Pack 4, also known as Version 7.0.0.4 is available for download.
8.5.5.2: WebSphere Application Server V8.5.5 Fix Pack 2
IBM WebSphere Virtual Enterprise Version 7.0 Fix Pack 5, also known as Version 7.0.0.5 is available for download.
8.5.5.3: WebSphere Application Server V8.5.5 Fix Pack 3
8.5.5.4: WebSphere Application Server V8.5.5 Fix Pack 4
8.5.5.5: WebSphere Application Server V8.5.5 Fix Pack 5
IBM WebSphere Virtual Enterprise Version 7.0 Fix Pack 6, also known as Version 7.0.0.6 is available for download.
8.5.5.6: WebSphere Application Server V8.5.5 Fix Pack 6
8.5.5.7: WebSphere Application Server V8.5.5 Fix Pack 7
8.5.5.8: WebSphere Application Server V8.5.5 Fix Pack 8
8.5.5.9: WebSphere Application Server V8.5.5 Fix Pack 9
8.5.5.10: WebSphere Application Server V8.5.5 Fix Pack 10
8.5.5.11: WebSphere Application Server V8.5.5 Fix Pack 11
8.5.5.12: WebSphere Application Server V8.5.5 Fix Pack 12
8.5.5.13: WebSphere Application Server V8.5.5 Fix Pack 13
8.5.5.14: WebSphere Application Server V8.5.5 Fix Pack 14
8.5.5.15: WebSphere Application Server V8.5.5 Fix Pack 15
8.5.5.14: WebSphere Application Server V8.5.5 Fix Pack 14
APAR status
Closed as program error.
Error description
When using APC.predictor=CPU, the power allocation does not account for CPU overload protection.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of the application placement * * controller in WebSphere Virtual Enterprise * **************************************************************** * PROBLEM DESCRIPTION: This APAR corrects problems with the * * application placement controller CPU * * predictor, multi-cell configurations, * * and AIX/POWER uncapped partitions. * **************************************************************** * RECOMMENDATION: * **************************************************************** CPU predictor 1) When using the CPU predictor (APC.predictor=CPU) in a multi-cell topology, the demand information for a cluster in a point cell is not sent to the application placement controller (APC) in the center cell. This prevents the APC from starting additional cluster members when demand increases for the clusters in the point cell. Elasticity 2) When using APC elasticity with AIX/POWER uncapped partitions, elastic adds and removes occur based on the total available capacity of a node (partition), which includes entitled capacity and shared capacity. However, the available shared capacity can change quickly and leave a cluster significantly below its required capacity. 3) After an elasticity operation completes, a waiting period follows, as configured in the "minimum time between placement change" setting. This time period allows the topology to adjust to the recently completed elasticity operation before initiating another operation. However, during certain timing conditions, the sleep period might be incorrectly interrupted, and placement decisions are initiated prematurely. 4) Fundamentally, elasticity add operations occur based on demand exceeding the capacity. There are additional constraints that allow or prevent elasticity operations, for example maximum instances. An unnecessary constraint incorrectly checks for demand information from non-production servers, for example node agent. During certain conditions, the unnecessary constraint can prevent elasticity add operations from occurring. Cluster capacity 5) APC uses cluster demand statistics from autonomic request flow manager (ARFM) to determine the percentage of the node capacity that should be allocated to each cluster member of a node. If a cluster does not have any demand, the APC uses an alternate calculation to determine the cluster capacity. The wrong cluster capacity calculation is used for clusters with demand and results in low cluster capacity calculation, which can lead to unnecessary queuing. This issue occurs when at least one cluster has no demand, and the remaining clusters have demand. The clusters with demand incorrectly use the capacity calculation of the clusters without demand.
Problem conclusion
The following code changes were made to resolve the listed limitations: 1) Demand information is now correctly sent from point cells to the center cell when using CPU predictor. 2) Elasticity adds on AIX/POWER uncapped partitions now occur based on entitled capacity. When demand exceeds the entitled capacity of a node (partition), an elasticity add operation is initiated. 3) The timing condition was corrected to prevent the elasticity sleep period from being interrupted. 4) The unnecessary constraint that prevented elasticity add operations from occurring was removed. 5) The incorrect cluster capacity calculation is no longer used on the wrong clusters. NOTE: Background CPU and CPU overload protection (COP) values are now included in the apc.log file to provide a better view of the conditions in a topology. This fix will be included in the next WebSphere Application Server V.8.5 fix, and in the next fix for WebSphere Virtual Enterprise V.7.0. Refer to the Recommended Updates page for delivery information: http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
Temporary fix
Comments
APAR Information
APAR number
PM82820
Reported component name
WAS VIRTUAL ENT
Reported component ID
5725C9203
Reported release
700
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2013-02-14
Closed date
2013-05-13
Last modified date
2018-10-17
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
WAS VIRTUAL ENT
Fixed component ID
5725C9203
Applicable component levels
R700 PSY
UP
Document Information
Modified date:
12 January 2022