[Users] High Availability

Mon Mar 18 05:18:28 UTC 2013

Tim Hildred:
>> If one host is down because of network interrupt or power
>> failure, the engine should know how many HA VMs are down and find
>> out the VM images on the storage domain to start the VM instances on
>> another host in the cluster. Why do we need power manager to be
>> configured?
> Power management allows the Manager to start highly available virtual machines on new hosts without worrying that virtual machine hard disk images will be corrupted.
>
> Imagine a situation in which the Manager cannot communicate with the host a highly available virtual machine is running on. If the host is still running as expected, and the virtual machine is also still running, the virtual machine is writing to its hard disk image.
Tim,

Thanks for clarification. That is what I expected.

>
> If the Manager starts that virtual machine on another host in the cluster, then both virtual machine instances will try and write to the disk image, and cause hard disk corruption.
>
> Power management lets the Manager be sure that only one instance of the highly available virtual machine is running, because the instance on the host the Manager couldn't communicate cannot survive a host reboot.
>
> Tim Hildred, RHCE
> Content Author II - Engineering Content Services, Red Hat, Inc.
> Brisbane, Australia
> Email: thildred at redhat.com
> Internal: 8588287
> Mobile: +61 4 666 25242
> IRC: thildred
>
> ----- Original Message -----
>> From: "Shu Ming" <shuming at linux.vnet.ibm.com>
>> To: "Tim Hildred" <thildred at redhat.com>
>> Cc: dron at redhat.com, Users at ovirt.org
>> Sent: Monday, March 18, 2013 1:31:12 PM
>> Subject: Re: [Users] High Availability
>>
>>
>> Tim,
>>
>> Thanks for your information. I am not sure why we need power
>> management to be configured for the hosts running HA virtual
>> machines.  We only need a method to check the VM or host status and
>> a method to restart the VM instances with existing VM images on
>> another host. Is it required to force powering down the failing host
>> forever to make sure the failing host will not come back to live
>> again?
>>
>>
>>
>>
>>      *
>> Power management must be configured for the hosts running the highly
>> available virtual machines.
>>      *
>> The host running the highly available virtual machine must be part of
>> a cluster which has other available hosts.
>>      *
>> The destination host must be running.
>>      *
>> The source and destination host must have access to the data domain
>> on which the virtual machine resides.
>>      *
>> The source and destination host must have access to the same virtual
>> networks and VLANs.
>>      *
>> There must be enough CPUs on the destination host that are not in use
>> to support the virtual machine's requirements.
>>      *
>> There must be enough RAM on the destination host that is not in use
>> to support the virtual machine's requirements.
>>
>>
>> Tim Hildred:
>>
>>
>> You might also find this helpful:
>> https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Virtualization/3.1/html/Administration_Guide/High_availability_considerations.html
>> The topics before and after it explain a bit more about high
>> availability.
>>
>> Tim Hildred, RHCE
>> Content Author II - Engineering Content Services, Red Hat, Inc.
>> Brisbane, Australia
>> Email: thildred at redhat.com Internal: 8588287
>> Mobile: +61 4 666 25242
>> IRC: thildred
>>
>> ----- Original Message -----
>>
>> From: "Dafna Ron" <dron at redhat.com> To: suporte at logicworks.pt Cc:
>> Users at ovirt.org Sent: Monday, March 18, 2013 4:46:51 AM
>> Subject: Re: [Users] High Availability
>>
>> I think that there is some confusion here so I will explain what are
>> the
>> configurations for fail-over.
>>
>> power management will reboot your host if a connectivity issue is
>> detected so all your vm's will be killed.
>> resilience policy will allow you to choose vm migration policy during
>> a
>> host failure and its configured in the cluster level (clusters ->
>> select
>> cluster -> general sub tab -> edit policy)
>> High Availability is configured only for servers type vm's and what
>> it
>> does is re-run the vm in case the pid of the vm is killed (so most
>> commonly, if you have power management configured, and the host is
>> rebooted, the vm will start automatically on a different host).
>>
>> so it really depends what you want. if you want vm migration than
>> look
>> into cluster policy, if you want a specific vm to always be up and
>> you
>> don't care about the other vm's than configure power management and a
>> HA
>> vm. it really depends on what you need.
>>
>>
>>
>>
>> On 03/17/2013 07:15 PM, suporte at logicworks.pt wrote:
>>
>> Is it Mandatory to have power manamement enabled? if yes what
>> equipment do you recommend to use with it?
>>
>> Regards
>> Jose
>>
>>
>> ----- Mensagem original -----
>> De: "René Koch" <r.koch at ovido.at> Para: suporte at logicworks.pt ,
>> Users at ovirt.org Enviadas: Domingo, 17 Março, 2013 16:47:41
>> Assunto: RE: [Users] High Availability
>>
>> Hi,
>>
>> You have to configure power management to make high availability
>> working and mark the vms high availability checkbox...
>>
>>
>> Regards,
>> René
>>   
>>   
>> -----Original message-----
>>
>> From:suporte at logicworks.pt <suporte at logicworks.pt> Sent: Sunday 17th
>> March 2013 17:28
>> To: Users at ovirt.org Subject: [Users] High Availability
>>
>> What should I need to configure to put HA working? I mean, when a
>> host broke all the VM automatically move to another host.
>> Do I need to have Power management enabled?
>>
>> Thanks
>> _______________________________________________
>> Users mailing list Users at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/users
>> _______________________________________________
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>> http://lists.ovirt.org/mailman/listinfo/users --
>> Dafna Ron
>> _______________________________________________
>> Users mailing list Users at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/users
>> _______________________________________________
>> Users mailing list Users at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/users
>>
>> --
>> ---
>> 舒明 Shu Ming
>> Open Virtualization Engineerning; CSTL, IBM Corp.
>> Tel: 86-10-82451626  Tieline: 9051626 E-mail: shuming at cn.ibm.com or
>> shuming at linux.vnet.ibm.com Address: 3/F Ring Building, ZhongGuanCun
>> Software Park, Haidian District, Beijing 100193, PRC

-- 
---
舒明 Shu Ming
Open Virtualization Engineerning; CSTL, IBM Corp.
Tel: 86-10-82451626  Tieline: 9051626 E-mail: shuming at cn.ibm.com or shuming at linux.vnet.ibm.com
Address: 3/F Ring Building, ZhongGuanCun Software Park, Haidian District, Beijing 100193, PRC