Hello, thank you for reply. I use GFS2 on compute nodes and VMs using qcow2 images sits on it.
I just found this https://bugzilla.redhat.com/show_bug.cgi?id=1356632 <https://bugzilla.redhat.com/show_bug.cgi?id=1356632> but no explanation. > On 28 Feb 2018, at 16:14, Andrew Price <[email protected]> wrote: > > On 28/02/18 14:03, FeldHost™ Admin wrote: >> Hello all, >> I have GFS2 cluster with KVM using qcow2 images. What is recommended IO >> mode? threads or native? I will be happy for recommendation and explanation. > > You'd likely get a better answer from the QEMU folks, but: > > As I understand it, with io=native qemu submits IO using OS-based aio > (io_submit()) and with io=threads it handles its own async io using > threading. To see what works best for you, it might be a good idea to do some > perf testing of your intended workload with each i/o mode. > > This talk covers the subject https://www.youtube.com/watch?v=Jx93riUF5_I > > You didn't mention whether you're using qcow2 _for_ gfs2 but be aware that > recent versions of libvirt will prevent non-raw images being made shareable > due to the potential for corruption. See > https://bugzilla.redhat.com/show_bug.cgi?id=1511480 for details. > > Hope this helps, > > Andy
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