[libvirt] Execute script on migration

Short question: What is the best way to run some script on VM migration? Detailed description: We use own system for volume management. Its based on md and we found it very flexible. Basic idea is that we have md mirror everywhere we can. This suits great for libvirt: We have a disk on iSCSI server, its "partioned" using device mapper, the resulting "partition" is member of md raid1, that raid is exported via iSCSI to the libvirt node, it is on the node included in another md raid1 and that "final" md raid is used as storage by the VM. This provides high level of abstraction that allows us to migrate the storage to another disk, another iSCSI server, etc... The only glitch is on live migration of the VM. It is possible to assemble and run the array on two nodes. Also all superblock modifications are done on first write to the array. However it would be more secure to stop the array after the source vm stops and before destination vm starts. What is the best way to run some script in this particular moment? I know we could create a new storage driver but I am not sure that it is the best option. -- Open WebMail Project (http://openwebmail.org)