Operating system user limit requirements (Linux and UNIX)
This topic outlines the recommended operating system user process resource limits (ulimits) on Linux® and UNIX operating systems.
- For some root installations, the Db2 database engine automatically raises ulimits where necessary based on the needs of the Db2 database system. However, there are situations when manual increase is needed even for root install.
- For all non-root installations, the Db2 database engine can update only the data, nofile, and fsize ulimits for the engine process up to the hard limits imposed by the system administrator.
In either case, it might be more practical to set the resource limits permanently on your system. Especially for non-root installations, the data, nofile, and fsize ulimit values should be set appropriately by an administrator after installing.
Recommended ulimit values for non-root installations
|Hard ulimit resource||Description||Minimum value||Recommended value||Command to query the value|
|data||Maximum private memory allowed for a process||The amount of memory available on the computer||Unlimited||ulimit -Hd|
|nofile||Maximum number of open files allowed for a process||Larger than the sum of all MAXFILOP database configuration parameters for all databases in the instance||65536||ulimit -Hn|
|fsize||Maximum file size allowed||Unlimited||Unlimited||ulimit -Hf|
If the minimum ulimit values are not met, the Db2 database engine could encounter unexpected operating system resource shortage errors. These errors can lead to a Db2 database system outage.
Contact a root user or a System Administrator if the ulimit values need to be updated for your non-root installation. Values for ulimits must be set manually, except on AIX® operating systems, where you can set ulimits by running the db2rfe command.