Question

Hight disk latency after changing kernel

Posted May 22, 2014 2.8k views
After changing kernel (upgrading from ubuntu 12.04 to 13.04) Munin start warning me the disk performance, like the following image. The avg io wait r/w stay at around 30 seconds. http://picpaste.com/disk_latency-TuJXeSQS.png But strangely enough, the server is running fine and no disk performance issue encountered. When I verify it with the following command, the result seems normal. sudo ioping /dev/vda -c 30 --- /dev/vda (device 30.0 GiB) ioping statistics --- 30 requests completed in 29.0 s, 911 iops, 3.6 MiB/s min/avg/max/mdev = 363 us / 1.1 ms / 3.4 ms / 668 us Does munin reading something wrong, or did I miss something?

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3 answers
Kernel infos:
Original kernel: vmlinuz-3.8.0-38-generic (12.04)
Current kernel: vmlinuz-3.13.0-24-generic (14.04)
Its seems to be a kernel bug. Have the same problem when I went from 13.10 to 14.04 see https://www.digitalocean.com/community/questions/14-04-munin-disk-latency

Thanks for the info.

I can safely ignore the warning now.
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