[Users] SPM not selected after host failed

[Itamar Heim]

On 09/20/2012 06:58 PM, Jorick Astrego wrote:
> On 09/20/2012 04:36 PM, users-request at ovirt.org wrote:
>> Date: Thu, 20 Sep 2012 17:13:25 +0300 From: Itamar Heim
>> <iheim at redhat.com> To: patrick.hurrelmann at lobster.de Cc:
>> users at ovirt.org Subject: Re: [Users] SPM not selected after host
>> failed Message-ID: <505B2485.9080604 at redhat.com> Content-Type:
>> text/plain; charset=ISO-8859-15; format=flowed On 09/20/2012 05:09 PM,
>> Patrick Hurrelmann wrote:
>>> >On 20.09.2012 16:01, Itamar Heim wrote:
>>>>> >>>Power management is configured for both nodes. But this might be
>>>>> the
>>>>> >>>problem: we use the integrated IPMI over LAN power management - and
>>>>> >>>if I pull the plug on the machine the power management becomes un-
>>>>> >>>available, too.
>>>>> >>>
>>>>> >>>Could this be the problem?
>>>> >>
>>>> >>yes... no auto recovery if can't verify node was fenced.
>>>> >>for your tests, maybe power off the machine for your tests as
>>>> opposed to
>>>> >>"no power"?
>>> >
>>> >Ugh, this is ugly. I'm evaluating oVirt currently myself and have
>>> >already suffered from a dead PSU that took down IPMI as well. I really
>>> >don't want to imagine what happens if the host with SPM goes down
>>> due to
>>> >a power failure :/ Is there really no other way? I guess multiple fence
>>> >devices are not possible right now. E.g. first try to fence via IPMI
>>> and
>>> >if that fails pull the plug via APC MasterSwitch. Any thoughts?
>> SPM would be down until you manually confirm shutdown in this case.
>> SPM doesn't affect running VMs on NFS/posix/local domains, and only
>> thinly provisioned VMs on block storage (iscsi/FC).
>>
>> question, if no power, would the APC still work?
>> why not just use it to fence instead of IPMI?
>>
>> (and helping us close the gap on support for multiple fence devices
>> would be great)
>>
>>
>> ------------------------------
>>
>> Message: 8
>> Date: Thu, 20 Sep 2012 16:24:47 +0200
>> From: Patrick Hurrelmann<patrick.hurrelmann at lobster.de>
>> To:users at ovirt.org
>> Subject: Re: [Users] SPM not selected after host failed
>> Message-ID:<505B272F.7000301 at lobster.de>
>> Content-Type: text/plain; charset=ISO-8859-15
>>
>> On 20.09.2012 16:13, Itamar Heim wrote:
>>> >On 09/20/2012 05:09 PM, Patrick Hurrelmann wrote:
>>>> >>On 20.09.2012 16:01, Itamar Heim wrote:
>>>>>> >>>>Power management is configured for both nodes. But this might
>>>>>> be the
>>>>>> >>>>problem: we use the integrated IPMI over LAN power management
>>>>>> - and
>>>>>> >>>>if I pull the plug on the machine the power management becomes
>>>>>> un-
>>>>>> >>>>available, too.
>>>>>> >>>>
>>>>>> >>>>Could this be the problem?
>>>>> >>>
>>>>> >>>yes... no auto recovery if can't verify node was fenced.
>>>>> >>>for your tests, maybe power off the machine for your tests as
>>>>> opposed to
>>>>> >>>"no power"?
>>>> >>
>>>> >>Ugh, this is ugly. I'm evaluating oVirt currently myself and have
>>>> >>already suffered from a dead PSU that took down IPMI as well. I
>>>> really
>>>> >>don't want to imagine what happens if the host with SPM goes down
>>>> due to
>>>> >>a power failure :/ Is there really no other way? I guess multiple
>>>> fence
>>>> >>devices are not possible right now. E.g. first try to fence via
>>>> IPMI and
>>>> >>if that fails pull the plug via APC MasterSwitch. Any thoughts?
>>> >
>>> >SPM would be down until you manually confirm shutdown in this case.
>>> >SPM doesn't affect running VMs on NFS/posix/local domains, and only
>>> >thinly provisioned VMs on block storage (iscsi/FC).
>>> >
>>> >question, if no power, would the APC still work?
>>> >why not just use it to fence instead of IPMI?
>>> >
>>> >(and helping us close the gap on support for multiple fence devices
>>> >would be great)
>>> >
>> Ok, maybe I wasn't precise enough. With power failure I actually meant a
>> broken PSU on the server and I won't be running any local/NFS storage
>> but only iSCSI.
>> But you're right with your point that in such situation fencing via APC
>> would be sufficient. I was mixing my different environments. My lab only
>> has IPMI right now, while the live environment most likely will have APC
>> as well.
>>
>> Regards
>> Patrick
> We don't have an APC, but we have dual psu's on two independent power
> feeds with independent backup power. Would we be sufficiently protected?
>

it is a matter of risk management - if both will fail, you will need to 
manually fence the host to free resources on it (VMs or SPM role).
if both power supplies go down, you usually notice and have bigger 
problems than this.