<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hello, thank you for reply. I use GFS2 on compute nodes and VMs using qcow2 images sits on it.<div class=""><br class=""></div><div class="">I just found this <a href="https://bugzilla.redhat.com/show_bug.cgi?id=1356632" class="">https://bugzilla.redhat.com/show_bug.cgi?id=1356632</a></div><div class=""><br class=""></div><div class="">but no explanation.<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 28 Feb 2018, at 16:14, Andrew Price <<a href="mailto:anprice@redhat.com" class="">anprice@redhat.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">On 28/02/18 14:03, FeldHost™ Admin wrote:<br class=""><blockquote type="cite" class="">Hello all,<br class="">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.<br class=""></blockquote><br class="">You'd likely get a better answer from the QEMU folks, but:<br class=""><br class="">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.<br class=""><br class="">This talk covers the subject <a href="https://www.youtube.com/watch?v=Jx93riUF5_I" class="">https://www.youtube.com/watch?v=Jx93riUF5_I</a><br class=""><br class="">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 <a href="https://bugzilla.redhat.com/show_bug.cgi?id=1511480" class="">https://bugzilla.redhat.com/show_bug.cgi?id=1511480</a> for details.<br class=""><br class="">Hope this helps,<br class=""><br class="">Andy<br class=""></div></div></blockquote></div><br class=""></div></body></html>