Hello Lionel, The kernel version is 2.6.32-279.2.1.el6.x86_64 (RHEL does not yet incorporate DRBD in the kernel natively). They (REDHAT), back port version 3.x.x kernel features into 2.6.xx code tree. So DRBD 8.4.2 is added as a loadable module. This problem that we are experiencing did not show up during testing. It only reared its ugly head after being rolled into production. I will take a look using "watch grep dirty /proc/vmstat".
Thanks James -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Lionel Sausin Sent: Tuesday, December 18, 2012 5:55 AM Cc: [email protected] Subject: Re: [DRBD-user] Still experiencing resource spikes Le 18/12/2012 10:30, Andreas Kurz a écrit : > That's quite a lot ... you also tuned vm.dirty_background_bytes and > vm.dirty_bytes to a reasonable low value? .... to avoid regular heavy > data write-out.... Regards, Andreas I'd look into this too, although with the given config and the default 10% threshold for background writes of dirty pages, it should kick in for ~12 Gbytes of dirty. Let's say 120 Gbits get sent over the 20Gb/s link, that clean all up in a few seconds shouldn't it ? I hope I'm not just adding noise, but if the kernel is old enough, there are cases where the write load is high enough for a sync operation to never end. Maybe that affects you? In any case, it's worth running a "watch grep dirty /proc/vmstat" while the i/o block : if the cleaner is kicking in, nr_dirty should decrease down to almost zero. If it goes down an up again and again, maybe the write load is too high for a sync() to finish. Lionel Sausin _______________________________________________ drbd-user mailing list [email protected] http://lists.linbit.com/mailman/listinfo/drbd-user _______________________________________________ drbd-user mailing list [email protected] http://lists.linbit.com/mailman/listinfo/drbd-user
