----- Original Message ----- From: "Laurie Harper" <l.harper@xxxxxxxxxxxxxxxx> To: <redhat-list@xxxxxxxxxx> Sent: Monday, October 20, 2003 12:21 PM Subject: RE: Physical Memory is beeing filled (RH7.1) > > Marcel, > > > > Your problem sounds like the Cache Swap bug: > > > >https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=89226#c15 > > > >Try doing the following: > > > >From the command line (as root) type: > > > >/sbin/sysctl -w vm.bdflush="30 500 0 0 2560 15360 60 20 0" > > > >Then edit your /etc/sysctl.conf file and add the following line: > > > >vm.bdflush="30 500 0 0 2560 15360 60 20 0" > > We have been experiencing similar issues on our web server, whereby > sudden swap usage spikes basically bring the server to a halt. While the > blame has been placed on high traffic by those helping to > troubleshooting the problem, I have felt that there was something else > going on, since most of the crashes we have experienced have actually > been random, often at low peak times, and the symptoms are nearly > identical to those documented in the bug report. While granted our web > traffic has been increasing steadily over the past few months, the > beginning of our crash problems was quite sudden, starting after we > migrated from RH 7.1 to 7.3 and then updated the kernel. It has been > extremely difficult to pinpoint the issue since there are virtual no > errors logged when this occurs, and there seems to be little to go on by > way of finding a common denominator between the incidents. > > A 'uname -a ; cat /proc/sys/vm/bdflush' returns: > > Linux server1.myserver.net 2.4.20-20.7smp #1 SMP Mon Aug 18 14:46:14 EDT > 2003 i686 unknown > 30 500 0 0 500 3000 60 20 0 > > A couple questions, first - all of the comments regarding this bug > appeared to reference RH9. Does the same apply to RH 7.3? Yes, this is a *kernel* issue, so whatever version of RH you're using, if you'v updated teh kernel, you can be susceptible. In fact, in comment #15, another user mentions that they started seeing this issue in RH 7.3 after they also updated their kernel. > Second, what > exactly do these bdflush figures represent, and how does the recommended > edit change the behavior of the system. Needless to say I am desperate > for a solution, but I am reluctant to make any changes without > understanding the potential effect on the system as a whole. As I understand it, the bdflush parameters deal with when the kernel flushes cache to disk and how it deals with virtual memory. I haven't dug deeply into it, as the options I detailed in my previous post have worked just dandy on our web server. Nevertheless, a google on "bdflush parameters" pulled up many hits, including: http://www.faqs.org/docs/securing/chap6sec68.html https://listman.redhat.com/archives/ext3-users/2003-May/msg00035.html https://listman.redhat.com/archives/ext3-users/2002-November/msg00073.html and many others. Ben -- redhat-list mailing list unsubscribe mailto:redhat-list-request@xxxxxxxxxx?subject=unsubscribe https://www.redhat.com/mailman/listinfo/redhat-list
