[ovirt-users] Storage types in oVirt

[Fernando Frediani]

Hi Nir,
Thanks for clarification.

Answering your questions: The intent was to use a Posix like filesystem 
similar to VMFS5 (GFS2, OCFS2, or other) where you have no choice for 
how the block storage is presented to multiple servers. Yes I heard 
about GFS2 escalation issues in the past, but thought it had been gone 
now a days, it seems not.

I had the impression that qcow2 images have both thin-provisioning and 
snapshot capabilities.

Regarding LVM I don't like the idea of having VMs buried into a LVM 
volume nor the idea of troubleshooting LVM volumes when necessary. 
Dealing with qcow2 images for every VM separately makes things much 
easier for doing several tasks. I would say that people coming from 
VMware would prefer to deal with a VMDK rather than a RDM LUN. In the 
other hand I have nothing to say about LVM performance.

Best
Fernando


Em 14/06/2016 16:35, Nir Soffer escreveu:
> On Tue, Jun 14, 2016 at 8:59 PM, Fernando Frediani
> <fernando.frediani at upx.com.br> wrote:
>> Hi there,
>>
>> I see that supported storage types in oVirt are: iSCSI, FCoE NFS, Local and
>> Gluster.
> We support iSCSI, FC, FCoE, NFS, Gluster, Ceph, Local and any posix like
> shared file system.
>
>> Specifically speaking about iSCSI and FCoE I see they use LVM on the block
>> storage level to store the Virtual Machines.
> To be more specific, we use lvm to create volumes. Each virtual machine disk
> use one volume and additional volume for each snapshot.
>
>> I just wanted to understand why the choice was to have LVM
> What would use use instead?
>
>> and if that is
>> the only option at the moment.
> This is the only option for block storage if you need snapshots or thin
> provisioning.
>
> If preallocated disk without snapshots is good enough for you, you
> can attach a LUN directly to a vm. This will give the best performance.
>
>> Was ever considered to have something like GFS2 ou OCFS2 in comparison with
>> VMFS5 and VMs running in qcow2 ou raw files on the top of it ?
> Any posix compatible file system can be used, using raw or qcow2 files.
>
> You can use GFS2, but I heard that it does not scale well.
>
>> I don't like LVM and have a strong preference for anything related to
>> storage that doesn't use it so the reason I'm looking for a different way to
>> use block storage without it having to be a LVM.
> You can use one of the file based storage options, or ceph.
>
> Whats wrong with lvm?
>
>
> Nir