While performing health checks of a Redis 2.8.19 setup running on an 30GB Ubuntu Server 14.04 LTS, I noticed that Linux memory usage was split as follows:

  • Used memory : 10GB
  • Cached Memory : 10GB
  • Free : 10GB

The Redis database is going to grow in the future and I need to forecast next memory upgrade. As a rule of thumb, I trigger an upgrade when 70% of any resource is reached.

My question is: Will Redis performance be impacted when Used memory + Cached memory will reach the 30 GB barrier? (and yes, swap is configured :) )

Kind Regards,



No, cached+buffered RAM is just the OS using any RAM it can, because not using it would be wasteful. It caches recent disk lookups in this spare memory until that memory is needed for more immediate things.

See also: Linux Ate My RAM

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