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From Alex Huang <>
Subject RE: [Discuss] Cpu and Ram overcommit.
Date Tue, 15 Jan 2013 22:49:52 GMT

A few comments.

- On your caveats, I think you should deploy 2b.  Accept the change but not add more VMs anymore.
 You can provide a warning.

- As for repeated alerts, that's a problem with the alert mechanism.  It should not repeat
alerts.  Fix it there.

On implementation:
- You need to add something more generic such as a cluster-details to cluster that allows
you retrieve what you want to add to it.  I don't see any reason to keep adding columns to
cluster/pods.  Cluster/pods are organization units.  We should add a details table (might
already there) to keep component details because no one else will use this detail information.
 I don't see why we need to add database columns for this.
- How are you planning to handle hypervisors that cannot overcommit cpu or ram?  To me this
needs capabilities added to the hypervisor caps table.
- This is a planner specific change.  Make sure the changes are localized in the planner.
 If there's anything you need to change in CloudStack core/server, please point that out in
a subtask for your bug and let me know.


> -----Original Message-----
> From: Bharat Kumar []
> Sent: Tuesday, January 08, 2013 3:16 AM
> To:
> Cc:
> Subject: Re: [Discuss] Cpu and Ram overcommit.
> Hi Hari,
>  A host can have more than one tag so we need not overwrite the inherited
> cluster  tag of a host, if a host specific tag is added.
> Bharat
> On Dec 26, 2012, at 11:32 AM, Bharat Kumar <>
> wrote:
> > Hi all,
> >
> > Presently in Cloudstack  there is a provision for cpu overcommit and no
> provision for the ram overcommit. There is no way to configure the
> overcommit ratios on a per cluster basis.
> >
> > So we propose to add a new feature to allow the ram overcommit and to
> specify the overcommit ratios ( cpu/ram ) on a per cluster basis.
> >
> > Motivation to add the feature:
> > Most of the operating systems and applications do not use the allocated
> resources to 100%. This makes it possible to allocate more resource than
> what is actually available.  The overcommitting of resources allows to run the
> underutilized VMs in fewer number of hosts, This saves money and power.
> Currently the cpu overcommit  ratio is a global parameter which means there
> is no way to fine tune or have a granular control over the overcommit ratios.
> >
> > This feature will enable
> > 1.) Configuring the overcommit ratios on a per cluster basis.
> > 2.) ram overcommit feature in xen and kvm. ( It is there for VMware.)
> > 3.) Updating the overcommit ratios of a cluster.
> >
> > Regards,
> > Bharat Kumar.

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