<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Oct 30, 2016 at 12:02 PM, Mike (maillinglists) <span dir="ltr"><<a href="mailto:maillist@probie.nl" target="_blank">maillist@probie.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi guys,<br>
<br>
There have been a few related questions already that I could find, but I did not find anything relating to my specific use case.<br>
<br>
Currently it is not possible to mix local storage with shared storage in the same datacenter.<br>
The reason seems to be because of the storage pool manager (SPM).<br>
This is a role in the datacenter provided to one specific host.<br>
<br>
While I understand that this makes having local storage impossible, I believe there is a use case to have local storage in a shared storage datacenter.<br></blockquote><div><br></div><div>Indeed, this is one of the more appealing use cases. There are others s well.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
Consider the following:<br>
I have a few applications that require 1 milli second latency and at most 2 milli second.<br></blockquote><div><br></div><div>For read, write or both?</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
That is not consistenly achievable with shared storage, to that end I added flash storage to a few hypervisors.<br></blockquote><div><br></div><div>You could have flash on your shared storage.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
About 5% of my servers require this and are not that resource hungry to require a dedicated physical server.<br>
That same 5% also has no requirement to be migrated if a host fails.<br>
<br>
So in short I have 5 heavy hosts running ovirt with a shared storage domain on NFS for 95% of my servers.<br>
All running fine, but I am now unable to run my remaining 5%.<br></blockquote><div><br></div><div>Perhaps, if there are no HA requirements, those VMs with local domain needs can be in their own DC, a local one? If it's just 5%, shouldn't be much of an effort?</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
To finish up my summary I have been testing various virtualization technologies, like VmWare and Hyper-V.<br>
They allow such configurations as I mentioned.<br>
<br>
I already had some chat on irc with various guys and they suggested that I put this on the mailing list, so here goes.<br>
<br>
My suggestion would be to evoluate from SPM to SDM.<br></blockquote><div><br></div><div>Easier said than done... We have worked on this for quite some time, it's not as easy as one might think.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
SDM stands for Storage Domain Manager.<br>
This would create the possibility to have all nodes in the datacenter participate in the storage handling.<br>
A extra benefit would be that local storage could be added.<br>
<br>
What do you think?<br></blockquote><div><br></div><div>There are other use cases we think flash on the host can be used, some may be of use for your use case.</div><div>For example, dm-cache[1].</div><div><br></div><div>We are still looking at this. I think Gluster already can make use it for cache, for example.</div><div>Y.</div><div><br></div><div>[1] <a href="https://people.redhat.com/mskinner/rhug/q1.2016/dm-cache.pdf">https://people.redhat.com/mskinner/rhug/q1.2016/dm-cache.pdf</a></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
Thanks for reading.<br>
<br>
Kind regards,<br>
Mike van Goor<br>
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