[ovirt-users] LVM2 Thinprovisioned

[Yaniv Kaul]

On Thu, Aug 11, 2016 at 8:27 PM, Fernando Frediani <
fernando.frediani at upx.com.br> wrote:

> Really ? That's pretty bad and another downside unfortunately.
>
> The fact that the only option for block storage is LVM (so there is not
> suitable Clustered Filesystem to run QCOW2 files) and now that LVM2
> Thinprovisioned is not supported can be a real issue where Thinprovisioned
> LUNs are not available in the Storage Controller.
>

I think you are missing the design of the oVirt storage sub-system. There
is no need to running a clustered filesystem - oVirt ensures only one host
access a logical volume (disk) at any given time.

I don't see exactly how LVM2 thin provisioning would have helped if the
storage controller does not support thin provisioning - if you give 1TB to
oVirt, why does it matter if it uses LVM TP or not? (and we can use qcow2
over LVM). Perhaps I'm missing something here.

Note that you can provision some LUN and when needed, just add more LUNs to
the storage domain. You can also extend it, of course.


> Have these topics ever came up in the feature/product management meetings
> are any of them something being considered ?
> The same way CPU and Memory overprovision are key features in order to
> justify the overall solution cost Storage Thinprovision equally necessary
> otherwise the Storage stuff end up costing more than half of whole platform
> solution.
>
> Thanks for the answer anyway. Hopefully at least LVM2 Thinprovisioning
> comes up anytime soon.


Don't think so. Why? As a replacement of qcow2? Not sure it's worth the
effort (you'll also need to get snapshots and all under LVM2 - what is the
clear benefit here?).
Y.


>
> Fernando
>
>
>
> Em 11/08/2016 12:54, Nir Soffer escreveu:
>
>> On Tue, Aug 9, 2016 at 3:16 PM, Fernando Frediani
>> <fernando.frediani at upx.com.br> wrote:
>>
>>> Hello all.
>>>
>>> When you use oVirt with a Block Storage the only option available to
>>> store
>>> de VMs is LVM.
>>>
>>> Does LVM in oVirt use Thinprovisoned (supported in LVM2) instead of
>>> having
>>> to use the SAN Thinprovisioned features ?
>>>
>> No, we use regular lvs. thin pool are not supported in a cluster.
>>
>> Using thin provisioned LUN for ovirt storage domain is the best option
>> (supported
>> since 4.0). We discard removed lvs, so you get back the storage on the
>> storage
>> server and can use it for other thin provisioned LUNs.
>>
>> Nir
>>
>
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