Martin Grotzke wrote: >> You could try different kernel I/O elevators and see if that improves >> something. >> >> I have made good experiences with elevator=deadline and elevator=noop. > Ok, great info. > > I'm not sure at which device to look honestly to check the current > configuration. > > mount/fstab shows the device /dev/mapper/VG01-www for the relevant > partition. When I check iostat high utilization is reported for the > devices dm-4 and sda (showing nearly the same numbers for util always), > so I suspect that dm-4 is mapped on sda. Use the option -N of "iostat" to see long device names. You can use "lvm" to figure out the mapping. > This is the current config: > $ cat /sys/block/sda/queue/scheduler > noop anticipatory deadline [cfq] > $ cat /sys/block/dm-4/queue/scheduler > none Do you mean literal "none" or do you mean that the file is empty? > Which of them should be changed? > I'll discuss this also with our hosting provider next week, he'll know > what has to be done. I'd just add "elevator=deadline" to the kernel line in /etc/grub.conf and reboot. At least if it is a dedicated database machine. But of course you want to change it on the fly first to test - not knowing the answer to your question, I would change it in both devices if I can. Yours, Laurenz Albe -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
