I can confirm this, drop_caches caused one of our RHEL 4 servers to crash. After this experience, the application admin refrained from asking us to "clear the memory" and found some other solution. :)
Morgan -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Corey Kovacs Sent: Thursday, September 23, 2010 11:14 PM To: Red Hat Enterprise Linux 5 (Tikanga) discussion mailing-list Subject: Re: [rhelv5-list] Tuning parameter drop_caches drop_caches is _not_ a tuning parameter, rather it's a tuning tool. You should _never_ do this on a production machine as very bad things can happen. It's supposed to be used to _reset_ a systems mem to a zero point in order to allow you to make changes and evaluate there effect, or debug a leak or what have you. -C On Thu, Sep 23, 2010 at 9:22 PM, Kyle O'Donnell <[email protected]> wrote: > you shouldn't *need* to do this at all. > > This gives a nice overview: > > http://www.linuxatemyram.com/ > > And if your devs don't believe have them try for themselves using: > > http://www.linuxatemyram.com/play.html > > --kyleo > > On Thu, 23 Sep 2010 13:03:55 -0700 (PDT), Srija > <[email protected]> wrote: >> Hi , >> >> In one of your xen guest ,one application is running and is consuming >> much memory, >> so almost every alternate day they ask to reboot the server. >> >> One of our admin suggested to use the following command. >> >> free && sync && echo 3 > /proc/sys/vm/drop_caches && free >> >> I was googling and there are mixed comments. Some are advising it is >> good , some are not. >> >> I was thinking that rather applying 'echo 3' , may be 'echo 1' will be >> good. >> >> As, >> >> To free pagecache: >> >> * echo 1 > /proc/sys/vm/drop_caches >> >> To free dentries and inodes: >> >> * echo 2 > /proc/sys/vm/drop_caches >> >> To free pagecache, dentries and inodes: >> >> * echo 3 > /proc/sys/vm/drop_caches >> >> Any advice will be really appreciated. Also do you think when we will >> execute the command, before that the application is needed to be >> stopped. >> >> Thanks in advance. > > _______________________________________________ > rhelv5-list mailing list > [email protected] > https://www.redhat.com/mailman/listinfo/rhelv5-list > _______________________________________________ rhelv5-list mailing list [email protected] https://www.redhat.com/mailman/listinfo/rhelv5-list _______________________________________________ rhelv5-list mailing list [email protected] https://www.redhat.com/mailman/listinfo/rhelv5-list
