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  • How can i clear all cache and buffered files in linux server (RHEL 5) ?
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marked as duplicate by Michael Hampton Sep 26 '13 at 3:47

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@Kumar - you might find the following thread on cache useful: serverfault.com/questions/105606/deleting-linux-cached-ram –  Patrick R Jan 30 '10 at 13:39
Someone may be able to suggest something else if you explained why you want to. vm/drop_caches wipes the OS's caches of files on disc; it has no semantic effect just kills performance, which makes it useful for performance testing and (mostly) nothing else. –  MarkR Jan 31 '10 at 21:34

3 Answers 3

up vote 3 down vote accepted

in this post it is explained how to do it:


but be sure to read the complete post for why or why not to clear the caches.

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As root: echo 3 > /proc/sys/vm/drop_caches

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sync && /sbin/sysctl -w vm.drop_caches=3 –  A-B-B Jan 21 '14 at 23:43

I had the same concerns about a heavy-handed cache on an embedded box running 2.6.15 (which does not have the proc file mentioned above). I did some experiments and found that one way to force the cache to clear is to create a ramdisk, fill it up with a huge temp file, and then delete the file. Works perfectly. Of course, what I proved was that Linux will indeed release the cache when absolutely ncessary. BTW changing swappiness to 0 or 100 had absolutely no observable effect on meminfo whatsoever.

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