[ovirt-devel] [monitoring][collectd] the collectd virt plugin is now on par with Vdsm needs

[Francesco Romani]

On 02/21/2017 11:55 PM, Yaniv Dary wrote:
>
>
> Yaniv Dary
> Technical Product Manager
> Red Hat Israel Ltd.
> 34 Jerusalem Road
> Building A, 4th floor
> Ra'anana, Israel 4350109
>
> Tel : +972 (9) 7692306
>         8272306
> Email: ydary at redhat.com <mailto:ydary at redhat.com>
> IRC : ydary
>
> On Feb 21, 2017 13:06, "Francesco Romani" <fromani at redhat.com
> <mailto:fromani at redhat.com>> wrote:
>
>     Hello everyone,
>
>
>     in the last weeks I've been submitting PRs to collectd upstream, to
>     bring the virt plugin up to date with Vdsm and oVirt needs.
>
>     Previously, the collectd virt plugin reported only a subset of metrics
>     oVirt uses.
>
>     In current collectd master, the collectd virt plugin provides all the
>     data Vdsm (thus Engine) needs. This means that it is now
>
>     possible for Vdsm or Engine to query collectd, not Vdsm/libvirt, and
>     have the same data.
>
>
>     There are only two caveats:
>
>     1. it is yet to be seen which version of collectd will ship all those
>     enhancements
>
>     2. collectd *intentionally* report metrics as rates, not as absolute
>     values as Vdsm does. This may be one issue in presence of
>     restarts/data
>     loss in the link between collectd and the metrics store.
>
>
> How does this work? 
> If we want to show memory usage over time for example, we need to have
> the usage, not the rate. 
> How would this be reported?

I was imprecise, my fault.

Let me retry:
collectd intentionally report quite a lot of metrics we care about as
rates, not as absolute values.
Memory is actually ok fine.

  a0/virt/disk_octets-hdc -> rate
  a0/virt/disk_octets-vda
  a0/virt/disk_ops-hdc -> rate
  a0/virt/disk_ops-vda
  a0/virt/disk_time-hdc -> rate
  a0/virt/disk_time-vda
  a0/virt/if_dropped-vnet0 -> rate
  a0/virt/if_errors-vnet0 -> rate
  a0/virt/if_octets-vnet0 -> rate
  a0/virt/if_packets-vnet0 -> rate
  a0/virt/memory-actual_balloon -> absolute
  a0/virt/memory-rss -> absolute
  a0/virt/memory-total -> absolute
  a0/virt/ps_cputime -> rate
  a0/virt/total_requests-flush-hdc ->  rate
  a0/virt/total_requests-flush-vda
  a0/virt/total_time_in_ms-flush-hdc -> rate
  a0/virt/total_time_in_ms-flush-vda
  a0/virt/virt_cpu_total -> rate
  a0/virt/virt_vcpu-0 -> rate
  a0/virt/virt_vcpu-1

collectd "just" reports the changes since the last sampling. I'm not
sure which is the best way to handle that; I've sent a mail to collectd
list some time ago, no answer so far.



-- 
Francesco Romani
Red Hat Engineering Virtualization R & D
IRC: fromani

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