[CentOS-virt] BAD disk I/O performance

Sun May 4 10:58:36 UTC 2014
Luca Gervasi <luca.gervasi at gmail.com>


i'm trying to convert my physical web servers to a virtual guest. What i'm
experiencing is a poor disk i/o, compared to the physical counterpart
(having strace telling me that each write takes approximately 100 times the
time needed on physical).

Tested hardware is pretty good (HP Proliant 360p Gen8 with 2xSAS 15k rpm 48
Gb Ram).

The hypervisor part is a minimal Centos 6.5 with libvirt.
The guest is configured using: VirtIO as disk bus, qcow2 storage format
(thick allocation), cache mode: none (needed for for live migration - this
could be changed if is the bottleneck), IO mode: default.

Is someone willing to give me some adivices? :)


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