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@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