Lets pool some knowledge together because at this point, I'm missing something. I've been doing all measurements with sar as bonnie, etc, causes builds to timeout. Problem: We're seeing slower then normal disk IO. At least I think we are. This is a PERC5/E and MD1000 array. When I try to do a normal copy "cp -adv /mnt/koji/packages /tmp/" I get around 4-6MBytes/s When I do a cp of a large file "cp /mnt/koji/out /tmp/" I get 30-40MBytes/s. Then I "dd if=/dev/sde of=/dev/null" I get around 60-70 MBytes/s read. If I "cat /dev/sde > /dev/null" I get between 225-300MBytes/s read. The above tests are pretty consistent. /dev/sde is a raid5 array, hardware raid. So my question here is, wtf? I've been working to do a backup which I would think would either cause network utilization to max out, or disk io to max out. I'm not seeing either. Sar says the disks are 100% utilized but I can cause major increases in actual disk reads and writes by just running additional commands. Also, if the disks were 100% utilized I'd expect we would see lots more iowait. We're not though, iowait on the box is only %0.06 today. So, long story short, we're seeing much better performance when just reading or writing lots of data (though dd is many times slower then cat). But with our real-world traffic, we're just seeing crappy crappy IO. Thoughts, theories or opinions? Some of the sysadmin noc guys have access to run diagnostic commands, if you want more info about a setting, let me know. I should also mention there's lots going on with this box, for example its hardware raid, lvm and I've got xen running on it (though the tests above were not in a xen guest). -Mike _______________________________________________ Fedora-infrastructure-list mailing list Fedora-infrastructure-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-infrastructure-list
