[ovirt-users] Spam Cluster Polcies

[Jiri Moskovcak]

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.

--J

>
> @Jirka?
>
>>
>>
>>
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