[Openstack] Disk performances much slower in Centos 6.7 guests than on ubuntu 14.04 guests

J-P Methot jpmethot at gtcomm.net
Thu Aug 20 17:39:04 UTC 2015


I've made a custom centos 6.7 image on a proxmox with kvm hypervisor
with the goal of using it with openstack. I setup all the necessary
cloud-init packages that are needed by openstack. Everything seems to
work fine on openstack, except that the drive speed in fio is about 50%
of what I can achieve on other images.

Basically, on a ubuntu 14.04 with the following FIO command, I can reach
about 1 GB/sec :

fio --name=testfio --filename=testfio --bs=4m --rw=write --size=5g

However, on my centos 6.7 image, I will only reach about 400 MB/sec. Why
is there such a huge discrepancy between both OS? I've always used
virtio, both on the proxmox hypervisor and on openstack.

Jean-Philippe Méthot
Administrateur système / System administrator
GloboTech Communications
Phone: 1-514-907-0050
Toll Free: 1-(888)-GTCOMM1
Fax: 1-(514)-907-0750
jpmethot at gtcomm.net

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