Can a virtual disk read speed of 400 MB/s be valid?

Question

linux

Hello! The question is, there is a server with 4 hdd WD black 1 TB each, united in hardware raid 10, it has centos 6.5 (linux 3.10, Xen 4.2).
There is a guest OS with Windows Server 2008 r2, management via virtlib, virtio is used as a driver.
The disk itself with the guest system is stored on a separate partition with ext4 in raw format.
I ran a reading speed test before installing paravirtual firewood for windows and after. Results in screenshots. The question is, can such a reading speed really reach, because I can hardly believe it .... and maybe one of the gurus will comment on some points?
before

after installing paravirtual drivers ( www.meadowcourt.org/downloads/)

Answer 1

It may well! At you RAID10, accordingly almost linear dependence on speed of all disks on reading. In other words, you are reading in 4 streams from all disks at once. And here virtio shows itself well.

Answer 2

average read access is a hardware characteristic of the disk, it could not be halved by the drivers. KMK here is reading from the cache in RAM
Increase the size of the readable gig file to 10-20 at once everything will be clear

Answer 3

Measurement through HD tune pro, measurement was made on the entire volume of the disk, with a block size of 64 KB
without firewood
with firewood