This is a multi-part message in MIME format. --------------5BAADD88E5767C79F227304D Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit 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@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@arsys.es <mailto:emayoral@arsys.es>> wrote:

On 30/04/18 14:05, Maor Lipchuk wrote:

...

On Mon, Apr 30, 2018 at 2:01 PM, Eduardo Mayoral <emayoral@arsys.es <mailto:emayoral@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.

--------------5BAADD88E5767C79F227304D Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body text="#000000" bgcolor="#FFFFFF"> <p>First, sorry that my previous answer went directly to you and not to the list. My mistake.</p> <p>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.</p> <p>Thanks for your help!<br> </p> <p><br> </p> <pre class="moz-signature" cols="72">Eduardo Mayoral Jimeno (<a class="moz-txt-link-abbreviated" href="mailto:emayoral@arsys.es">emayoral@arsys.es</a>) Administrador de sistemas. Departamento de Plataformas. Arsys internet. +34 941 620 145 ext. 5153</pre> <div class="moz-cite-prefix">On 30/04/18 14:48, Maor Lipchuk wrote:<br> </div> <blockquote type="cite" cite="mid:CAJ1JNOf_KjTnOUCxTUbDsBGpc0e1sVJE2PaoqqvPV_OEWPXk1A@mail.gmail.com"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <div dir="ltr"> <div>Will it help if you will have 2 local data centers?<br> </div> <div>and use the 'trick' with the detach/attach of the shared storage domain?</div> <div><br> </div> <div>Basically the architecture of oVirt does not relate clusters to storage domains.</div> <div>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.<br> </div> <div><br> </div> <div>Regards,</div> <div>Maor</div> </div> <div class="gmail_extra"><br> <div class="gmail_quote">On Mon, Apr 30, 2018 at 3:23 PM, Eduardo Mayoral <span dir="ltr"><<a href="mailto:emayoral@arsys.es" target="_blank" moz-do-not-send="true">emayoral@arsys.es</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <div text="#000000" bgcolor="#FFFFFF"> <div> <div class="h5"> On 30/04/18 14:05, Maor Lipchuk wrote:<br> <blockquote type="cite"> <div dir="ltr"><br> <div class="gmail_extra"><br> <div class="gmail_quote">On Mon, Apr 30, 2018 at 2:01 PM, Eduardo Mayoral <span dir="ltr"><<a href="mailto:emayoral@arsys.es" target="_blank" moz-do-not-send="true">emayoral@arsys.es</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span>On 30/04/18 12:51, Tony Brian Albers wrote:<br> > On 30/04/18 11:43, Eduardo Mayoral wrote:<br> >> Hi,<br> >><br> >>      I would like to set up a new oVirt deployment with hosts that have<br> >> the VMs running on local attached storage. I understand this has the<br> >> requirement of having each host in its own cluster (and own datacenter,<br> >> it seems, I understand the need for the dedicated cluster, not so much<br> >> for the dedicated datacenter).<br> >><br> >>      At the same time, I would like to have some shared storage domains<br> >> so I can use it to export VMs or migrate them around hosts (probably in<br> >> three stages, first migrate VM storage from local to the shared storage<br> >> domain, second migrate the host (probably not possible to do a "hot"<br> >> migration, but at least "cold"), third migrate the VM storage from the<br> >> shared storage domain to the local storage domain of the new host).<br> >><br> >>      So I thought maybe I can deploy a datacenter in shared storage mode,<br> >> with one cluster per host. Use one or two shared storage domains for<br> >> master and as an stage area for planned VM migrations as explained<br> >> before, and then configure several storage domains, one per host, as<br> >> posix FS . I would then deploy the VMs on the local posix FS storage<br> >> domains and set affinity rules for the VMs to their hosts as needed.<br> >><br> >>      Would this work? Is there a better way of achieving local storage<br> >> and retaining the ability to share storage among hosts and migrate VMs?<br> >><br> >><br> > Have you thought about using glusterfs? If hosts are physically close, <br> > that would probably be the best solution.<br> ><br> <br> </span>Actually, yes, I also had glusterfs in mind. However one of the main<br> reasons to use local storage is performance, and I am concerned about<br> the write latencies of gluster (If using gluster, I would handle things<br> so the VM runs on one of the gluster nodes hosting the VM data, so I<br> assume the read latency will be close to the one I would get with local<br> storage, but the gluster replica(s) will be on other hosts, so write<br> latency may be significantly worse).<br> <br> Thanks a lot for the suggestion, it is a good one, however, the original<br> question stands: Would this work? Is there a better way of achieving<br> <span>local storage and retaining the ability to share storage among hosts and<br> migrate VMs?<br> </span></blockquote> <div><br> </div> <div>Hi Eduardo,</div> <div>We support <span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">shared storage domains in a local data center since </span>oVirt 4.1.</div> <div>Will this help you by any chance?</div> </div> </div> </div> </blockquote> <br> </div> </div> Hi, Moar,<br>     <br>     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.<br> <br>     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?<br> <br>     Thanks for your help!<br> <br> --<br> Eduardo Mayoral.<br> <br> </div> </blockquote> </div> <br> </div> </blockquote> <br> </body> </html> --------------5BAADD88E5767C79F227304D--