[ovirt-users] Poor guest write speeds

[Alan Murrell]

For my latest test, I installed CentOS7 on my server and then  
installed the libvirt/KVM virtualization group.  I created a Win7  
guest VM giving it 2GB RAM, 1 vCPU, and 60GB HDD. I did not specify  
anything for the HDD type; just whatever the default is for libvirt.

The install of Win7 went *way* faster than any bare metal install I  
have ever done of Win7, and also faster than the ESXi install I had  
done earlier.

Once installed, I downloaded the same "Parkdale" HDD testing  
application I have been using, and used the same settings.  The write  
test results were about 100 MByte/s.  I ran the test several times,  
including rebooting between tests, and the results came back consistent.

As a baseline, I ran the following modified 'dd' write test on the  
server itself:

dd bs=1M count=4000 if=/dev/zero of=test conv=sync

with the following results:

4000+0 records in
4000+0 records out
4194304000 bytes (4.2 GB) copied, 39.349 s, 107 MB/s

So now the question becomes, why would I be getting such a huge  
difference in oVirt?

Thanks.

-Alan