Free Up RAM in Redhat & CentOS Linux

Memory normally is occupied by 3 main objects, caches debtries and inodes. However you can free memory at times with the following commands.

1. Sync essentials to disk first by running the following command:

Code:

sync  

2. Cleanup the RAM:

Writing to this will cause the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become free.

To free pagecache:

Code:

echo 1 > /proc/sys/vm/drop_caches

To free dentries and inodes:

Code:

echo 2 > /proc/sys/vm/drop_caches

To free pagecache, dentries and inodes:

Code:

echo 3 > /proc/sys/vm/drop_caches

As this is a non-destructive operation and dirty objects are not freeable, the user should run `sync' first.