[ovirt-devel] Shared gluster storage domain for templates

[Sven Kieske]

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On 03.07.2015 22:31, Christopher Pereira wrote:
> Hi,
> 
> I'm trying to setup a gluster data storage domain exclusively for 
> templates (read only) and share it among different geo distributed
> ovirt data centers. I believe this is a common requirement. Do you
> know if there is a clean/efficient way to do this?
> 
> My experiment:
> 
> I geo-replicated the templates storage domain in order to keep a
> local copy on each data center for faster new VM instantiation or
> thin template provisioning. The problem I faced is it's not
> possible to import a replicated storage domain when the original
> Storage Domain UUID is already registered in the same Engine
> installation. A workarround was to detach the original SD (from
> Data Center 1) and attach the replicated SD (on Data Center 2)...or
> use another Engine installation. This works, but still requires to
> detach and reattach the storage domain.
> 
> Is there anyway to copy a storage domain or change its UUID? I
> guess I can change the Storage Domain UUID (dirname and 
> dom_md/metadata), but I'm afraid of the multiple references inside
> the binary file 'dom_md/ids'.
> 
> BTW, using a gluster replica-n volume seems to be the cleanest
> solution because this way Engine would only be showing one single
> templates storage domain (ideal). The only reason I didn't go this
> way is because it is not designed between geo distributed data
> networks.

This is somehow related to my old bug report:
https://bugzilla.redhat.com/show_bug.cgi?id=1130090

In short: ovirt has some places where it wants a "name"
to be unique instead of using the UUID.

also it want's this to be unique system wide, instead of
a more sane and flexible approach like data center wide, or
cluster wide unqiueness.

It would also be a nice RFE to have read only storage
which can be attached to multiple DCs at the same time.

This already works for ISO domains, so you
should be able to add the functionality to also
use this as a template source.

But maybe all this pain will go away when there are
no more storage domains.
btw will this feature make it for 3.6 or later? I know
decommission of master storage domain is suited for 3.6:
https://bugzilla.redhat.com/show_bug.cgi?id=1185830

kind regards

Sven

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