Blip is absolutely correct. But it depends on how you are copying files.. If you're using Windblows Exploder, it will most likely fail and abort, but that's a problem with the Windows design.. it's not a cluster problem.
Here's a short history of clustering that you need to understand...
If you were to run a 600MB Movie file off of your cluster resource.. say an AVI in Media Player on Windows XP. If the cluster resource were to failover - your movie file would be interrupted and it would start over from the beginning. This tells you that Windows is closing the file for you when the 'blip' occurrs.
Take that same movie file, run it on a Windows 98 box. Run it from the cluster just like before. Failover the cluster resource to the other node. Your movie will blip, but it will pick up where it left off as soon as the other cluster resource comes online. This proves that on Windows 98, the file isn't actually closed.
So this would prove to you that the cluster is doing it's job just fine, but Windows XP is actually what is causing the file copy to fail. There is a TID or Appnote that talks about this, but I'd have to dig it up.
When a cluster fails over, there is always a blip where the service will not be available. With a lot of services, you'd never notice this. Like, GroupWise - you shouldn't notice anything. iFolder shouldn't be affected. Web Services will hardly be noticeable. But doing a file copy, because the file is open, then the cluster resource deactivates off of one node and then reactivates - there will be a blip. This is true with other clustering technologies as well.
BTW, if you're serious about your cluster, you should put in a 3rd node.
Marvin Huffaker, MCNE