[Users] Designate Master Storage Domain

[Itamar Heim]

On 08/16/2013 04:46 PM, Dead Horse wrote:
> Pausing the VM's can work in certain situations for simple maintenance.
> However suppose the purpose of the storage shutdown is to move data
> around for certain VM's or perhaps change that particular underlying
> storage filesystem or hardware. Thus some of the VM's will have to be
> down for sure however pausing them all because of the aforementioned
> would not be an option since it would take hours or days depending on
> the amount of data and the degree of change.
>

I'm sorry - how is pausing VMs running from a storage domain moved to 
maint is related to master storage domain?

> - DHC
>
>
> On Fri, Aug 16, 2013 at 12:14 AM, Karli Sjöberg <Karli.Sjoberg at slu.se
> <mailto:Karli.Sjoberg at slu.se>> wrote:
>
>     __
>     tor 2013-08-15 klockan 10:46 -0500 skrev Dead Horse:
>>     Itamar this is true (I have noted occasional timing issues with it
>>     actually working).
>>     But what if as the administrator I have a specific storage domain
>>     in mind that I would like to have become the master (in the case
>>     of more then two)?
>>
>>
>>     @Karli
>>
>>     The idea is not to not have to shut down all the VM's or the
>>     engine just to maintenance a storage domain(s) that may happen to
>>     be on disparate storage servers
>>     .
>
>     Yes I understood that. My suggestion was a workaround until such
>     operations are possible, that we use to minimize downtime as much as
>     possible, to *pause* the VM's, shut down engine, maintenance, bring
>     engine and VM's back. Since the VM's only was paused and engine shut
>     down, the VM's just continue going happily unknowing exactly from
>     where they were, and a reboot of a storage takes at most 5mins,
>     which means 5mins total of downtime in the cloud environment for
>     that quarter, which is acceptable for just about any SLA.
>
>     /Karli
>
>
>>
>>     - DHC
>>
>>
>>
>>     On Thu, Aug 15, 2013 at 9:37 AM, Itamar Heim <iheim at redhat.com
>>     <mailto:iheim at redhat.com>> wrote:
>>
>>         On 08/15/2013 06:18 AM, Dead Horse wrote:
>>
>>             Is there any method of designating which domain should be
>>             the master
>>             storage domain or forcibly changing the role to a
>>             different storage domain?
>>
>>             EG: Given the following example
>>
>>             Storage Domain A (Master) --> NFS --> Storage Server 1
>>             Storage Domain B --> NFS --> Storage Server 2
>>
>>             One wants to do maintenance to Storage Server 1 but in
>>             doing so the
>>             Master storage domain is hosted from Storage Server 1.
>>             Thus the net
>>             result of taking down Storage Server 1 is that one must
>>             also take down
>>             Storage Server 2.
>>
>>             Thus we know we must shut down VM's from Storage Domain A
>>             to maintenance
>>             Storage Server 1. Suppose however that VM's are running
>>             that we don't
>>             want to shut down and are hosted from Storage Domain B via
>>             Storage Server 2.
>>
>>             We would want to be able to promote Storage Domain B to
>>             Master so that
>>             we can take down Storage Domain A to do maintenance to
>>             Storage Server 1.
>>
>>             Once we are done with maintenance to Storage Server 1 we
>>             can bring
>>             Storage Domain A back on line, re-designate it as Master
>>             if desired and
>>             bring it's VM's back online.
>>
>>             I know I have seen this occur automatically to a point
>>             when a Storage
>>             Domain goes missing that is the Master Domain but I have
>>             not noted any
>>             manual method of doing so given the above scenario.
>>
>>             - DHC
>>
>>
>>
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>>
>>
>>         my understanding is you can move the storage domain A which is
>>         master to maint. engine will promote storage domain B to
>>         master and everything should continue working as is.
>>
>>
>>
>
>     --
>
>     Med Vänliga Hälsningar
>     -------------------------------------------------------------------------------
>     Karli Sjöberg
>     Swedish University of Agricultural Sciences
>     Box 7079 (Visiting Address Kronåsvägen 8)
>     S-750 07 Uppsala, Sweden
>     Phone: +46-(0)18-67 15 66 <tel:%2B46-%280%2918-67%2015%2066>
>     karli.sjoberg at slu.se <mailto:karli.sjoberg at adm.slu.se>
>
>