Re: Possible to use libgfapi with libvirt in CentOS 6.5?

[Lalatendu Mohanty <lmohanty@xxxxxxxxxx>]

On 03/28/2014 05:37 PM, Dave Christianson wrote:

I've come across individual posts from people who supposedly have done this in CentOS6.5. Basically, all that is shown in the posts is the XML file generated, no mention of *how* that file is generated. Virt-manager has no provision for attaching directly to the gluster volume except as a mount. Neither virt-manager nor virt-install recognize the gluster:// type.

Supposedly earlier versions of RHEL used qemu-kvm as a wrapper for qemu-system-x86_64, however in 6.5 qemu-kvm is its own binary. Qemu-kvm also doesn't recognize the gluster:// type.

Debian and Ubuntu supposedly have the newer versions of gluster and qemu/libvirt availabe (ppa's?). Maybe I'll test Wheezy...

Red Hat seems content to do their own thing. Although the verisons of libvirt and qemu are older, libgfapi is supposed to have been backported. It's a shame that full functionality is not included. It's mindboggling seeing that Red Hat owns glusterfs, you would think full support for the backend would have been included in their product. If it is, as you say, that RH includes this functionality only to RHN subscribers and is not made available downstream to CentOS/SL, and unless I can find a repository with the latest full versions of qemu & libvirt, then CentOS simply will not work.

I am pretty sure there would be some technical reason behind not having all support for libgfapi. May be somebody who has more knowledge about specifics should give some more context. 

Regarding making functionality only to RHN subscribers and is not made available downstream to CentOS/SL,

• It might not be related to source availability as libvirt is available under LGPL [2] , so nothing can be changed here about availability of source.
  
• CentOS is built upon a particular version of RHEL which does not have the relevant package (which already been mentioned) [1]

To address these issues CentOS community is now working on special interest groups, where new and relevant packages can be provided which is is not present as part of core CentOS. Which is the exactly the case here. In the same line CentOS Storage SIG [3]  was proposed and already approved by CentOS board.

CentOS Storage SIG will provide all relevant packages for GlusterFS. The packages can have required upstream patches, so that community will not face an issue like this. The initiative has just started and we are working on it. Hopefully CentOS Storage SIG will solve a lot of problems like this and provide a easy way to deploy GlusterFS.

[1] http://wiki.centos.org/FAQ/General#head-d22edba1476618760e12d5d9529f354d2d46953a
[2] http://opensource.org/licenses/lgpl-license.html
[3] http://wiki.centos.org/SpecialInterestGroup/Storage/Proposal

Thanks,
Lala

On Fri, Mar 28, 2014 at 3:13 AM, Harshavardhana <harsha@xxxxxxxxxxxxxxxxxx> wrote:

Virt-manager / libvirt is yet to expose perhaps this functionality -
but as far as i remember libvirt should be doing this as a
pass-through for the URL's which have been passed  as
"<schema>://<server>/<volname>"

Does libvirt 'invoke' fuse when passed "gluster://" schema?

On Thu, Mar 27, 2014 at 5:34 PM, Dave Christianson
<davidchristianson3@xxxxxxxxx> wrote:
> Good Evening,
>
> I have read that libgfapi has been backported to qemu-kvm in RHEL 6.5 (and
> by virtue CentOS and SL). However I am unable to figure out how to actually
> make it work as described. Virt-manager still only seems to support
> glusterfs volumes via fuse.
>
> I can use qemu-img to create a disk image on gluster://<server>/<Volume>.
> But virt-manager can only use it from a fuse mounted fileshare. There seems
> to be no ability to attach in virt-manager directly to the image on
> glusterfs using libgfapi.
>
> All documents I've found describe the use of the command
> "qemu-system-x86_64," however that command does not exist in CentOS 6.5.
> That appears to be the only way to start the domain using libgfapi. So
> basically, I can create an image via libgfapi but cannot do anything useful
> with it.
>
> Should I be able to do this? If so, what's the procedure? Or is CentOS/RHEL
> 6.5 just not fully integrated? I really want to be able to use libgfapi and
> avoid the performance penalty of fuse. Should I just grab & compile the
> latest verisons of libvirt and qemu-kvm?
>
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> Gluster-users mailing list
> Gluster-users@xxxxxxxxxxx
> http://supercolony.gluster.org/mailman/listinfo/gluster-users



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