Thanks I think I got it now. I can adjust my cluster policy accordingly
- Original Message -
From: Gilad Chaplik gchap...@redhat.com
To: Jiri Moskovcak jmosk...@redhat.com
Cc: Maurice James mja...@media-node.com, users users@ovirt.org
Sent: Monday, June 30, 2014 9:20:31 AM
Subject: Re: [ovirt-users] Spam Cluster Polcies
- Original Message -
From: Jiri Moskovcak jmosk...@redhat.com
To: Gilad Chaplik gchap...@redhat.com
Cc: Maurice James mja...@media-node.com, users users@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 jmosk...@redhat.com
To: Gilad Chaplik gchap...@redhat.com, Maurice James
mja...@media-node.com
Cc: users users@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 mja...@media-node.com
To: users users@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?
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