Paging situation - for DB2 v12 and supporting products - CA Detector/SSA/Sysview for DB2

Products

• Subsystem Analyzer for DB2 for z/OS
• Database Management for DB2 for z/OS - Performance Suite
• Database Management for DB2 for z/OS - SQL Performance Suite
• Detector for DB2 for z/OS

Issue/Introduction

There is a paging situation, in which local files are filling up. An investigation via EPV statistics shows  that there is a trend – at about 21:30-23:00 there is a small leap, that adds up every day. Investigations have shown that usually (but not always) on that time big Unloads (via BMC NGT Unload or DB2 regular unload) are being executed. There is no certain proof that the paging problem is caused by a certain product, but it happens on the unload night routine mostly, and can even occur  from running two products at the same time.

 

 

Environment

Release : 20.0

Component : CA Detector for DB2 for z/OS

Resolution

These numbers show very low G-COMMON (64 bit shared memory) usage Collection Xmanager G-Common Storage
4K CELL POOL --> 172K
32K CELL POOL --> 128K
QBAC CELL POOL --> 6.92M
STTS CELL POOL --> 10.55M
STATS CELL POOL --> 503.75K
On the XMAN private storage. we have a hard limit of 2G at which point we start shutting collections down. So our memory usage looks clean.