All About Linux Memory Usage by the Oracle Database
Frits Hoogland, Accenture Enkitec
Memory usage of a virtual memory systems like linux always have been shrouded in mystery, with admins setting parameters by best practice rather than based on measurable facts specific for that machine and workload. This presentation explains how memory is allocated and used on Linux (and when it isn’t!), after which different database memory scenario’s are replayed on a virtual machine showing how memory allocations behave. Because of the delayed allocation, oversubscription of memory will in most cases not become visible at database startup time, but rather after running for some time, depending on memory need, which can be minutes, but also very easily after a few days. Without awareness of linux memory allocation strategies, oversubscription indicators like sudden swapping will seem to happen random. The gist if the talk is not Oracle database specific, however, it will use Oracle database scenario’s.
More details coming soon.