Ubuntu 12.04 old libvirt version bug with default VM’s config

Under Ubuntu 12.04 old libvirt version installed by default cause to bug with default VM’s config. Libvirt created xml config file for VM without driver options:

For example:

That’s why you can see performance degradation with IO system. For example i have about 3MB/s disk read/write performance.

Fix:

1. Copy your VM config file to .bak
2. Undefine VM (virsh undefine )
3. Edit VM config:

Add:
cache=’writeback’ io=’native’

For example:

4. Define VM config

Author: GergunD

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