Using top and looki at 'wa' value can tell you I/O wait time for each CPU
Dont forget to press "1" to expand list of CPUs

Tasks: 501 total,   4 running, 497 sleeping,   0 stopped,   0 zombie
Cpu0  : 31.9%us, 52.7%sy,  0.0%ni, 15.1%id,  0.0%wa,  0.0%hi,  0.3%si,  0.0%st
Cpu1  : 29.7%us,  7.6%sy,  0.0%ni, 62.1%id,  0.0%wa,  0.0%hi,  0.7%si,  0.0%st

Also, there is handy tool called: iotop which can tell how much process writes and read. We can see on our 6Gpbs SATAIII interface with SSD disks, the interfaces is being maxed out with writes at ~500MBs

At the end 7.2k disks can be easily maxed out while running a few VMs so no surprise here.

Lastly, setup some monitoring for example munin, its quite handy :

http://demo.munin-monitoring.org/disk-day.html



On Mon, Feb 8, 2016 at 1:58 PM Gokan Atmaca <linux.gokan@gmail.com> wrote:
> Are the disk partitions properly aligned to 4k boundary on the host (and in
> the guests too) ?
>
There are 5 in total server. 32G ram. 2T r1 (soft) disk.


On Mon, Feb 8, 2016 at 9:41 PM, Zoltan Frombach <zoltan@frombach.com> wrote:
> Are the disk partitions properly aligned to 4k boundary on the host (and in
> the guests too) ?
>
> See
> http://www.ibm.com/developerworks/library/l-linux-on-4kb-sector-disks/index.html
> and this:
> http://unix.stackexchange.com/questions/247387/check-if-partitions-are-aligned-properly-for-performance
>
>
> On 2/8/2016 8:12 PM, Gokan Atmaca wrote:
>>
>> Hello
>>
>> I use KVM. In a virtual machine "jbd2 dm-0" disk I / O is very
>> increases. It consumes up to 99%. For this reason, slowing down the
>> other virtual machine. What should I do to solve the problem. ?
>>
>> Thanks..
>> _______________________________________________
>> CentOS-virt mailing list
>> CentOS-virt@centos.org
>> https://lists.centos.org/mailman/listinfo/centos-virt
>
>
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