[CentOS-virt] KVM

Mon Feb 8 20:13:28 UTC 2016
Marcin Figura <mfigura at mintel.com>

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 at 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 at 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..
> >> _______________________________________________
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> >
> >
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