Re: [Users] [vdsm] glusterfs and ovirt

On 05/17/2012 11:05 PM, Itamar Heim wrote: > On 05/17/2012 06:55 PM, Bharata B Rao wrote: >> On Wed, May 16, 2012 at 3:29 PM, Itamar Heim<iheim(a)redhat.com> wrote: >>> On 05/15/2012 07:35 PM, Andrei Vakhnin wrote: >>>> >>>> Yair >>>> >>>> Thanks for an update. Can I have KVM hypervisors also function as >>>> storage >>>> nodes for glusterfs? What is a release date for glusterfs support? >>>> We're >>>> looking for a production deployment in June. Thanks >>> >>> >>> current status is >>> 1. patches for provisioning gluster clusters and volumes via ovirt >>> are in >>> review, trying to cover this feature set [1]. >>> I'm not sure if all of them will make the ovirt 3.1 version which is >>> slated >>> to branch for stabilization June 1st, but i think "enough" is there. >>> so i'd start trying current upstream version to help find issues >>> blocking >>> you, and following on them during june as we stabilize ovirt 3.1 for >>> release >>> (planned for end of june). >>> >>> 2. you should be able to use same hosts for both gluster and virt, >>> but there >>> is no special logic/handling for this yet (i.e., trying and providing >>> feedback would help improve this mode). >>> I would suggest start from separate clusters though first, and only >>> later >>> trying the joint mode. >>> >>> 3. creating a storage domain on top of gluster: >>> - expose NFS on top of it, and consume as a normal nfs storage domain >>> - use posixfs storage domain with gluster mount semantics >>> - future: probably native gluster storage domain, up to native >>> integration with qemu >> >> I am looking at GlusterFS integration with QEMU which involves adding >> GlusterFS as block backend in QEMU. This will involve QEMU talking to >> gluster directly via libglusterfs bypassing FUSE. I could specify a >> volume file and the VM image directly on QEMU command line to boot >> from the VM image that resides on a gluster volume. >> >> Eg: qemu -drive file=client.vol:/Fedora.img,format=gluster >> >> In this example, Fedora.img is being served by gluster and client.vol >> would have client-side translators specified. >> >> I am not sure if this use case would be served if GlusterFS is >> integrated as posixfs storage domain in VDSM. Posixfs would involve >> normal FUSE mount and QEMU would be required to work with images from >> FUSE mount path ? >> >> With QEMU supporting GlusterFS backend natively, further optimizations >> are possible in case of gluster volume being local to the host node. >> In this case, one could provide QEMU with a simple volume file that >> would not contain client or server xlators, but instead just the posix >> xlator. This would lead to most optimal IO path that bypasses RPC >> calls. >> >> So do you think, this use case (QEMU supporting GlusterFS backend >> natively and using volume file to specify the needed translators) >> warrants a specialized storage domain type for GlusterFS in VDSM ? > > I'm not sure if a special storage domain, or a PosixFS based domain > with enhanced capabilities. > Ayal? Related Question: With QEMU using GlusterFS backend natively (as described above), it also means that it needs addnl options/parameters as part of qemu command line (as given above).

How does VDSM today support generating a custom qemu cmdline. I know VDSM talks to libvirt, so is there a framework in VDSM to edit/modify the domxml based on some pre-conditions, and how / where one should hook up to do that modification ? I know of libvirt hooks framework in VDSM, but that was more for temporary/experimental needs, or am i completely wrong here ? Irrespective of whether GlusterFS integrates into VDSM as PosixFS or special storage domain it won't address the need to generate a custom qemu cmdline if a file/image was served by GlusterFS. Whats the way to address this issue in VDSM ? I am assuming here that special storage domain (aka repo engine) is only to manage image repository, and image related operations, won't help in modifying qemu cmd line being generated. [Ccing vdsm-devel also] thanx, deepak _______________________________________________ vdsm-devel mailing list vdsm-devel(a)lists.fedorahosted.org https://fedorahosted.org/mailman/listinfo/vdsm-devel