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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