On 02/26/2017 03:13 PM, Yaniv Dary wrote:

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.

Can you CC on that thread?

I don't know how ES would work with rates at all. 

I want to be able to show CPU usage over time and I need to know if its 80% or 10%.

Thanks to the awkward gmail interface I can't reply to myself and CC other people, but I can share the link:

https://mailman.verplant.org/pipermail/collectd/2017-January/006965.html

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