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ProTop Trends: Server - Swap Usage

Definition of terms found in the graph legend

  • swap.out (int, bytes): data swapped out since last boot calculated from page number
  • total (int, bytes): total swap memory
  • free (int, bytes): free swap memory
  • used (int, bytes): used swap memory
  • swap.in (int, bytes): data swapped in since last boot calculated from page number

What to look for? Here a scenario ...

In these two images showing swap.out:


and swap.in:


We are seeing more swap activity than we would like.  

We might ask, "Is swappiness on this server set correctly?"  

If it is the default setting, even with a large amount of real memory the system will still move things to swap. Setting swappiness to 1 should reduce/eliminate it.