I'm using AIX 6.1 and for testing.
I want to clear the file system cache.
Something similar a this on linux : echo 2 > /proc/sys/vm/drop_caches

Is this possible?

2 Answers 2


Failing an actual method to flush the cache you might be able to get away with tuning some VMM parameters to effectively flush your cache.

vmo -L

Look at setting minperm% and maxperm% very low and strict_maxperm to 1. I don't have an AIX box handy to test what values it will let you set but I'm assuming 0 would fail, maybe:

vmo -o minperm%=1 -o maxperm%=1 -o strict_maxperm=1 -o minclient%=1 -o maxclient%=1

Monitor with vmstat -v to see when/if it applies. You might need to do something memory intensive to trigger the page replacement daemon into action and take care of that 1%.

cat "somefile_sized_1%_of_memory" > /dev/null 

Then reset them back to your normal values.

  • Perfectly and acceptable workaround! I just set the maxclient% to a value equal of minperm% and strict_maxclient=1, in less of 2 minutes 16GB of memory was freed. Now I will back the original values. Thanks!
    – ceinmart
    Jan 8, 2014 at 17:18

The only thing I could find was this command :

mount -o rbrw

Link : https://www.ibm.com/developerworks/community/forums/html/topic?id=77777777-0000-0000-0000-000014315545#77777777-0000-0000-0000-000014315663

Other option will be unmonting the file-system wich will dump the cache.

  • Hy @Boogy, I already tested this before... not work for me because I need execute the command with users accessing the FS. This option need to umount first, which make it unfeasible.
    – ceinmart
    Jan 8, 2014 at 15:04

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