[one-users] CPU and Memory Overcommitment

[Carlos Martín Sánchez]

It depends, you can configure a HA setup and have another opennebula gain
control of the cloud, and restart the VMs.

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Join us at OpenNebulaConf2013 <http://opennebulaconf.com> in Berlin, 24-26
September, 2013
--
Carlos Martín, MSc
Project Engineer
OpenNebula - The Open-source Solution for Data Center Virtualization
www.OpenNebula.org | cmartin at opennebula.org |
@OpenNebula<http://twitter.com/opennebula><cmartin at opennebula.org>


On Thu, Sep 5, 2013 at 3:24 PM, Igor Laskovy <igor.laskovy at gmail.com> wrote:

> Ok, thanks. And one more: is it true that if I lost front-end host along
> with some hypervisor hosts died VMs don't restart on alive hosts?
>
>
> On Thu, Sep 5, 2013 at 1:34 PM, Carlos Martín Sánchez <
> cmartin at opennebula.org> wrote:
>
>> Hi,
>>
>> On Wed, Sep 4, 2013 at 12:03 PM, Igor Laskovy <igor.laskovy at gmail.com>
>>  wrote:
>>
>>> One further question - how Fault Tolerance mechanism (via HOST_HOOK)
>>> deal with this reservations? Does it reserved some "slots" for VMs recovery?
>>>
>>
>>  OpenNebula does not have any kind of reservation scheduling.
>>
>>
>>> If not and if I at every turn manually don't control available resources
>>> on hosts those may cause to situation when my automatically recreated VMs
>>> will stuck in placement state.
>>>
>>
>> Yes, that may happen. But you still can implement a reservation mechanism.
>> I'm sure there are better alternatives, but this is a quick idea:
>>
>> - Disable half of your hosts.
>> - For each enabled host, define a failover_host = <id> attribute in its
>> template, pointing to one of the disabled hosts
>> - Modify the fault tolerance hook to make it enable the defined failover
>> host.
>>
>> Another quick hack is to create a dummy VM for each VM that you need to
>> guarantee that reserved slot, using the requirements and current_vms
>> features to deploy it in a host different from the original VM. Then delete
>> that VM when the hook recreates the original VM...
>>
>>
>> Regards.
>>
>> --
>> Join us at OpenNebulaConf2013 <http://opennebulaconf.com> in Berlin,
>> 24-26 September, 2013
>> --
>> Carlos Martín, MSc
>> Project Engineer
>> OpenNebula - The Open-source Solution for Data Center Virtualization
>> www.OpenNebula.org | cmartin at opennebula.org | @OpenNebula<http://twitter.com/opennebula><cmartin at opennebula.org>
>>
>>
>> On Wed, Sep 4, 2013 at 12:03 PM, Igor Laskovy <igor.laskovy at gmail.com>wrote:
>>
>>> Thank you for reply!
>>>
>>> One further question - how Fault Tolerance mechanism (via HOST_HOOK)
>>> deal with this reservations? Does it reserved some "slots" for VMs
>>> recovery? If not and if I at every turn manually don't control available
>>> resources on hosts those may cause to situation when my automatically
>>> recreated VMs will stuck in placement state.
>>>
>>>
>>> On Wed, Sep 4, 2013 at 12:23 PM, Carlos Martín Sánchez <
>>> cmartin at opennebula.org> wrote:
>>>
>>>> Hi,
>>>>
>>>> On Tue, Sep 3, 2013 at 1:32 PM, Igor Laskovy <igor.laskovy at gmail.com>wrote:
>>>>
>>>>> Hello all!
>>>>>
>>>>> I found that this already have discussed not so far from now -
>>>>> http://comments.gmane.org/gmane.comp.distributed.opennebula.user/10568
>>>>>
>>>>> As understand for now about Memory over-commitment for production I
>>>>> can forget ;)
>>>>>
>>>>> For CPU over-commitment I can only use CPU & VCPU attributes, right?
>>>>>
>>>>
>>>> That's right
>>>>
>>>>
>>>>>  If I will, for example, set CPU to 0.2, than host will do only
>>>>> reservation of processor time for that VM OR do limit ether, so this VM
>>>>> will limited of 1/5 of one physical/logical hardware core?
>>>>>
>>>>
>>>> We enforce the CPU reserved at hypervisor level with cgroups for kvm,
>>>> credit scheduler for xen, and the esx cpu scheduler for vmware
>>>>
>>>> Regards
>>>>
>>>> --
>>>> Join us at OpenNebulaConf2013 <http://opennebulaconf.com/> in Berlin,
>>>> 24-26 September, 2013
>>>> --
>>>> Carlos Martín, MSc
>>>> Project Engineer
>>>> OpenNebula - The Open-source Solution for Data Center Virtualization
>>>> www.OpenNebula.org <http://www.opennebula.org/> |
>>>> cmartin at opennebula.org | @OpenNebula <http://twitter.com/opennebula>
>>>>
>>>
>>>
>>>
>>> --
>>> Igor Laskovy
>>> facebook.com/igor.laskovy
>>> studiogrizzly.com
>>>
>>
>>
>
>
> --
> Igor Laskovy
> facebook.com/igor.laskovy
> studiogrizzly.com
>
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