[ovirt-users] Trying to understand the mixed storage configuration options.

[Nir Soffer]

On Thu, May 12, 2016 at 10:50 AM, Gianluca Cecchi
<gianluca.cecchi at gmail.com> wrote:
> On Thu, May 12, 2016 at 4:50 AM, Jason Ziemba <jason at ziemba.net> wrote:
>>
>> I'm fairly new to oVirt (coming from ProxMox) and trying to wrap my head
>> around the mixed (local/NAS) data domain options that are available.
>>
>> I'm trying to configure a set of systems to have local storage, as their
>> primary data storage domain, though also want to have the ability to have a
>> NAS based data domain for guests that are 'mobile' between hosts.  Currently
>> I'm able to do one or the other, but not both (so it seems).
>>
>> When I put all of the systems in to a single cluster (or single
>> data-center) I'm able to have the shared data domain, though have only found
>> the ability to configure one system for local storage (not all of them).
>> When I split them out in to separate data centers, they all have their local
>> data domain working, but only a single dc is able to access the shared data
>> domain at a time.
>>
>> Am I missing something along the way (probably fairly obvious) that does
>> exactly what I'm outlining, or is this functionality not available by
>> design?
>>
>> Any assistance/guidance is greatly appreciated.
>>
>> _______________________________________________
>>
>>
>
> Already asked about one month ago. See thread here:
> http://lists.ovirt.org/pipermail/users/2016-April/038911.html
>
> The last comment by Neil was to provide reasons for this need, as probably
> it is not on the roadmap.
> But 4.0 version is only at alpha stage so we can influence it, if we push.

No chance for 4.0.

It is unlikely that we will work on it before removing the spm and the
master domain. Without spm and master domain, this change should be
easier.

> Actually already in 2013 it was asked and Itamar at that time wrote that the
> team was working on eliminating this limit.. don't know what exactly was the
> design limitation from a technical point of view. See thread with question
> from (another one... ;-) Jason  here:
> http://lists.ovirt.org/pipermail/users/2013-July/015400.html
>
> and Itamar final comment here:
> http://lists.ovirt.org/pipermail/users/2013-July/015413.html

Having access to all storage domains from all hosts in a dc is the basic
design assumption. Having some domains which are accessible only from
some hosts is a major change.

> I'm favorable to have the chance to configure inter-mixed storage, local and
> not, especially for testing purposes, but not only, where you have plenty of
> storage you cannot dedicate to oVirt VMs now.
> The workaround is to have it seen as NFS storage, but it makes sense only
> for one-host configuration in my opinion, and it overloads network when it
> is not necessary.
>
> Can we vote for it? Do we need to open an RFE?

I think we have one, and you can vote on the bug (I don't have the bug
number).

> BTW: I think insipration should also come form what the leaders are doing
> (in the positive sense) and in what's new for vSphere 6 here:
> https://www.vmware.com/files/pdf/vsphere/VMW-WP-vSPHR-Whats-New-6-0-PLTFRM.pdf
>
> you find explicitly inside the "VMware vSphere Fault Tolerance
> Enhancements", so in a critical infrastructure point:
>
> "
> There have also been enhancements in how vSphere FT handles storage. It now
> creates a complete copy of
> the entire virtual machine, resulting in total protection for virtual
> machine storage in addition to compute
> and memory. It also increases the options for storage by enabling the files
> of the primary and secondary
> virtual machines to be stored on shared as well as local storage. This
> results in increased protection,
> reduced risk, and improved flexibility

Can you explain what they are doing and how it can benefit ovirt?

Nir