[ovirt-users] Spam Cluster Polcies

[Gilad Chaplik]

----- Original Message -----
> From: "Jiri Moskovcak" <jmoskovc at redhat.com>
> To: "Gilad Chaplik" <gchaplik at redhat.com>
> Cc: "Maurice James" <mjames at media-node.com>, "users" <users at ovirt.org>
> Sent: Monday, June 30, 2014 4:19:06 PM
> Subject: Re: [ovirt-users] Spam  Cluster Polcies
> 
> On 06/30/2014 03:11 PM, Gilad Chaplik wrote:
> > ----- Original Message -----
> >> From: "Jiri Moskovcak" <jmoskovc at redhat.com>
> >> To: "Gilad Chaplik" <gchaplik at redhat.com>, "Maurice James"
> >> <mjames at media-node.com>
> >> Cc: "users" <users at ovirt.org>
> >> Sent: Monday, June 30, 2014 3:57:29 PM
> >> Subject: Re: [ovirt-users] Spam  Cluster Polcies
> >>
> >> On 06/30/2014 01:53 PM, Gilad Chaplik wrote:
> >>> ----- Original Message -----
> >>>> From: "Maurice James" <mjames at media-node.com>
> >>>> To: "users" <users at ovirt.org>
> >>>> Sent: Friday, June 27, 2014 1:20:23 AM
> >>>> Subject: [ovirt-users] Spam  Cluster Polcies
> >>>>
> >>>> Can someone explain the cluster policies to me? The explanation at
> >>>> http://www.ovirt.org/Features/Even_VM_Count_Distribution is not quite
> >>>> clicking for me.
> >>>>
> >>>>
> >>>>
> >>>>       * HighVMSCount - Maximum VM limit. Exceeding it qualifies the host
> >>>>       as
> >>>>       overloaded. ( Understood )
> >>>
> >>> minimal #vms on host to enable the module (i.e worst host should have
> >>> more
> >>> than HighVMSCount vms).
> >>>
> >>>>       * MigrationThreshold - defines a buffer before we start migrating
> >>>>       VMs
> >>>>       from the host ( Not quite grasping. If my High limit is 5 does
> >>>>       this
> >>>>       mean
> >>>>       that it will only begin to move VMs when the count reaches 10? )
> >>>
> >>> don't think that there's any relation with "HighLimit".
> >>> It means that migration will happen only if there is a difference of X
> >>> vms
> >>> or more between worst host (source host) to destination host.
> >>>
> >>> let say that you have 2 hosts. one has 10 vms and the second 8. if the
> >>> threshold is 3, no migration will happen (10-8 !> 3).
> >>
> >> - exactly
> >>
> >>>
> >>>>       * SPMVMCountGrace - defines how many slots for VMs should be
> >>>>       reserved
> >>>>       on
> >>>>       SPM hosts (the SPM host should have less load than others, so this
> >>>>       variable defines how many VM less it should have) ( Does this mean
> >>>>       that
> >>>>       if I have a host with only 3 VMs the SPM will 3 VMs minus the
> >>>>       SpmWmGrace? Or is this HighVmCount minus SpmVmGrace count?)
> >>>
> >>> you're right, the SPM host will have current + grace VMs in terms of
> >>> module
> >>> calculations.
> >>> I think that this is problematic, it is likely to be selected as worst
> >>> host
> >>> candidate and that's not the wanted behavior iiuc
> >>> imo, we should subtract (-) in overloaded hosts and add (+) in
> >>> underutilized.
> >>
> >> - I think it's correct as it is, if the SpmVmGrace+currentVms >
> >> HighVmCount it is overutilized and should be freed if possible.
> >
> > not sure I understand, let's take an example
> > 2 hosts: spm: 8 #vms, hsm: 8 #vms.
> > SPMVMCountGrace = 2.
> > in this case the 'worst' host will be the SPM... shouldn't we deduct 2 from
> > spm and not add? we want less noise there.
> >
> 
> - that's correct, the SPM will be marked as overutilized and the engine
> will try to find a host to migrate some vms from the SPM. The SpmGrace
> is not about lowering the noise it's about keeping the host less
> utilized by running less VMs on it (which will also lower the noise,
> because it will give the SPM host worse score when looking for target to
> migrate to)

got it, thanks :-)

> 
> --J
> 
> >>
> >> --J
> >>
> >>>
> >>> @Jirka?
> >>>
> >>>>
> >>>>
> >>>>
> >>>> _______________________________________________
> >>>> Users mailing list
> >>>> Users at ovirt.org
> >>>> http://lists.ovirt.org/mailman/listinfo/users
> >>>>
> >>
> >>
> 
>