[ovirt-users] Posix FS as alternative to local storage?

[Eduardo Mayoral]

First, sorry that my previous answer went directly to you and not to the
list. My mistake.

Well, detaching and attaching shared storage domains is not the solution
I was hoping for, but at least it gives me an option to migrate VMs
between hosts. It is either that or gluster (thanks, Tony), depending on
the performance impact.

Thanks for your help!


Eduardo Mayoral Jimeno (emayoral at arsys.es)
Administrador de sistemas. Departamento de Plataformas. Arsys internet.
+34 941 620 145 ext. 5153

On 30/04/18 14:48, Maor Lipchuk wrote:
> Will it help if you will have 2 local data centers?
> and use the 'trick' with the detach/attach of the shared storage domain?
>
> Basically the architecture of oVirt does not relate clusters to
> storage domains.
> Storage domains are part of a data center while hosts are part of a
> cluster which is part of a data center. I guess that is the reason why
> it will be more problematic to declare cluster as local.
>
> Regards,
> Maor
>
> On Mon, Apr 30, 2018 at 3:23 PM, Eduardo Mayoral <emayoral at arsys.es
> <mailto:emayoral at arsys.es>> wrote:
>
>     On 30/04/18 14:05, Maor Lipchuk wrote:
>>
>>
>>     On Mon, Apr 30, 2018 at 2:01 PM, Eduardo Mayoral
>>     <emayoral at arsys.es <mailto:emayoral at arsys.es>> wrote:
>>
>>         On 30/04/18 12:51, Tony Brian Albers wrote:
>>         > On 30/04/18 11:43, Eduardo Mayoral wrote:
>>         >> Hi,
>>         >>
>>         >>      I would like to set up a new oVirt deployment with
>>         hosts that have
>>         >> the VMs running on local attached storage. I understand
>>         this has the
>>         >> requirement of having each host in its own cluster (and
>>         own datacenter,
>>         >> it seems, I understand the need for the dedicated cluster,
>>         not so much
>>         >> for the dedicated datacenter).
>>         >>
>>         >>      At the same time, I would like to have some shared
>>         storage domains
>>         >> so I can use it to export VMs or migrate them around hosts
>>         (probably in
>>         >> three stages, first migrate VM storage from local to the
>>         shared storage
>>         >> domain, second migrate the host (probably not possible to
>>         do a "hot"
>>         >> migration, but at least "cold"), third migrate the VM
>>         storage from the
>>         >> shared storage domain to the local storage domain of the
>>         new host).
>>         >>
>>         >>      So I thought maybe I can deploy a datacenter in
>>         shared storage mode,
>>         >> with one cluster per host. Use one or two shared storage
>>         domains for
>>         >> master and as an stage area for planned VM migrations as
>>         explained
>>         >> before, and then configure several storage domains, one
>>         per host, as
>>         >> posix FS . I would then deploy the VMs on the local posix
>>         FS storage
>>         >> domains and set affinity rules for the VMs to their hosts
>>         as needed.
>>         >>
>>         >>      Would this work? Is there a better way of achieving
>>         local storage
>>         >> and retaining the ability to share storage among hosts and
>>         migrate VMs?
>>         >>
>>         >>
>>         > Have you thought about using glusterfs? If hosts are
>>         physically close,
>>         > that would probably be the best solution.
>>         >
>>
>>         Actually, yes, I also had glusterfs in mind. However one of
>>         the main
>>         reasons to use local storage is performance, and I am
>>         concerned about
>>         the write latencies of gluster (If using gluster, I would
>>         handle things
>>         so the VM runs on one of the gluster nodes hosting the VM
>>         data, so I
>>         assume the read latency will be close to the one I would get
>>         with local
>>         storage, but the gluster replica(s) will be on other hosts,
>>         so write
>>         latency may be significantly worse).
>>
>>         Thanks a lot for the suggestion, it is a good one, however,
>>         the original
>>         question stands: Would this work? Is there a better way of
>>         achieving
>>         local storage and retaining the ability to share storage
>>         among hosts and
>>         migrate VMs?
>>
>>
>>     Hi Eduardo,
>>     We support shared storage domains in a local data center
>>     since oVirt 4.1.
>>     Will this help you by any chance?
>
>     Hi, Moar,
>        
>         Thanks for your fast reply! This helps partly, but does not
>     quite solve my needs. If I understood correctly, I can have a
>     shared storage attached to a local storage Data Center. However I
>     cannot share a shared storage among datacenters. I can detach the
>     shared storage domain from one datacenter and attach it to another
>     one, but I cannot "Share" the shared storage as in: both hosts see
>     it at the same time, as I would expect it to be the case with a
>     shared storage domain in a regular shared data center.
>
>         Root of the problem for me actually is: I can totally
>     understand that host with local storage must "live" in a dedicated
>     cluster. But, why does it also need a dedicated data center entity?
>
>         Thanks for your help!
>
>     --
>     Eduardo Mayoral.
>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ovirt.org/pipermail/users/attachments/20180430/46704f04/attachment.html>