I added a shadow volume on an san iscsi lun to an (old)existing volume and
tried doing an initial migration to move everything not modified for more
then 2 years to that new volume.

That pretty much killed the server as it tried to move a large part of the
volume to the new shadow volume. The load went up to 30.xx, killing
everyones connection to the server and then to 65.xx which triggered the ASR

Any ideas on how to get things over more smoothly for the initial fill ?