Slow KVM I/O speeds when host node much faster (virtio)

I'm running a single CentOS 6 virtual machine on a SolusVM KVM hostnode using virtio.

On the hostnode, I can get (elevator:deadline):

# dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 5.38596 s, 199 MB/s

but on the VM, I only get (elevator: noop):

root@grasshopper [~]# dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 18.4232 s, 58.3 MB/s

I can actually feel the sluggishness within the VM itself...

The hostnode has 4 x 1TB in RAID-10 with hardware raid + bbu. From your experience, does 199MB/s sound reasonable for a hard-drive only array?

Does anyone know why this is, and what I can do to fix it? Perhaps the LVM is misaligned? If so, how can I tackle that problem?

Thanks in advance,