Comment 5 for bug 1453039

Please make your hard drive is high-performance enough to deal with loads of fsync system calls which are caused by apt-get and debootstrap while building OS image. For example, if you use qemu + libvirt for your lab, then try cache='unsafe' which make host system ignore all fsync system calls from a guest OS.

 <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' cache='unsafe' io='native'/>
      <source file='/var/lib/libvirt/images/fuel-master.qcow2'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x09' function='0x0'/>
    </disk>