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b9e95491d1
For some reason these have been stored in /var/lib, although other drivers (e.g. qemu and lxc) store their state files in /var/run. It's much nicer to store state files in /var/run because it is automatically cleared out when the system reboots. We can then use existence of the state file as a convenient indicator of whether or not a particular network is active. Since changing the location of the state files by itself will cause problems in the case of a *live* upgrade from an older libvirt that uses /var/lib (because current status of active networks will be lost), the network driver initialization has been modified to migrate any network state files from /var/lib to /var/run. This will not help those trying to *downgrade*, but in practice this will only be problematic in two cases 1) If there are networks with network-wide bandwidth limits configured *and in use* by a guest during a downgrade to "old" libvirt. In this case, the class ID's used for that network's tc rules, as well as the currently in-use bandwidth "floor" will be forgotten. 2) If someone does this: 1) upgrade libvirt, 2) downgrade libvirt, 3) modify running state of network (e.g. add a static dhcp host, etc), 4) upgrade. In this case, the modifications to the running network will be lost (but not any persistent changes to the network's config).
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>