Freeing up memory from RHEL cache

To my knowledge, a vanilla install of RHEL 5.x has no configuration to automate the release of the accumulated memory within the cache. This can become an issue when there's no more free memory for other applications.
July 27, 2012
Unix

There seems to be a number of monitoring software available though I am unable to recommend any to date.

I was experiencing a caching memory issue as demonstrated. The picture represents the memory accumulation over a couple of days whilst the system was idle. When I execute the 'free -m' command, it's noticeable that the free available memory in decreasing and the cache accumulation is increasing over time.

https://technicalconfessions.com/images/postimages/postimages/_40_3_freeing_up_memory_from_cache.png

The quick solution to free-up the cached memory was to execute the following command:

echo 3 > /proc/sys/vm/drop_caches

As soon as this command is executed by the root user, the memory from the cache is immediately released and now accessible as available memory. In this example I managed to free-up around 1.5Gb of memory.

About the author

Daniel is a Technical Manager with over 10 years of consulting expertise in the Identity and Access Management space.
Daniel has built from scratch this blog as well as technicalconfessions.com
Follow Daniel on twitter @nervouswiggles

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