[libvirt-users] How to best I/O performance for Window2008 and MSSQL guest VM

[Blair Bethwaite]

Hi Roberto,

What is the cpu and memory configuration of your guest? Are you
pinning to dedicated CPUs, are you exposing host topology and cpu
features, do you have dedicated I/O threads? Are you backing the guest
memory with hugepages? All of the above will likely increase
performance and minimise noise.

Cheers,

On 6 December 2016 at 05:13, Roberto Fichera <kernel at tekno-soft.it> wrote:
> Hi There,
>
> I've moved some Windows2012 with MSSQL VMs from an hold ESXi 5.5 machine
> to a more recent and powerful machine running Fedora 24 x86_64 and related libvirt + KVM
> virtualization. I've moved the VMs filesystem to LVM slices and installed the VirtIO drivers
> in to all Windows VMs. I've also set both Disk and Network interface to work using VirtIO.
> So far so good everything works pretty fine. Now I would like to tune at best the MSSQL VM
> for both Disk and Network interfaces in order to get the best performance possible.
>
> Regarding network interface I've set it to work as bridge instead to go through to macvtap, so I'm
> not sure what is the best in this case.
>
> Regarding disk, since it's LVM I've chosen to go to cache mode none and IO mode native. Also
> here cannot judge what's the best setup for the workload. I'm undecided to use IO mode threads
> along directsync cache mode.
>
> Finally I've set "ionice -c 1 -p <qemu-pid> -n 0" and "renice -n -10 <qemu-pid>" for the interested
> VM that I want to get best performance possible.
>
> Even with the above setup, the MSSQL VM has performance similar to the old machine running
> ESXi 5.5, so does anyone can suggest where too look at and/or what would be the right setup?
>
> Thanks in advance.
> Roberto Fichera
>
>
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-- 
Cheers,
~Blairo