[Users] Designate Master Storage Domain

[Dead Horse]

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.

- DHC


On Fri, Aug 16, 2013 at 12:14 AM, Karli Sjöberg <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> 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
> karli.sjoberg at slu.se <karli.sjoberg at adm.slu.se>
>
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