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TIBCO ActiveSpaces® 4.8.0

# Memory Usage Considerations with the node_read_cache_size Option

The tibdg grid create command comes with the `node_read_cache_size` option. This property governs the size of the read cache allotted to a node.

Here are some memory usage considerations when you are assigning a size to the read cache:

- If the RAM on a node's host exceeds the amount of data persisted by the node, increasing the `node_read_cache_size` value to match the size of the uncompressed data set yields an improved random read performance.
- If the data set is larger than the host's RAM, increasing the `node_read_cache_size` value can negatively affect the random read performance. In such instances, the read cache of the application comes at the expense of the page cache of the operating system.

- If `node_read_cache_size` is a significant percentage of the host RAM, the operating system must be configured to prevent swapping of the node application for optimal performance. Example:

  - On Linux, you might have to reduce the value of /proc/sys/vm/swappiness or disable `swap`.
  - In Docker, you can modify the `--memory-swappiness run` parameter to prevent swapping.

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