I think we've gone around looking for these at various times in the past and always been able to cull a few of the worst offenders. I was thinking more along the line of coming up with a more-lasting solution involving policy announcements and monitoring. NFS is convenient for a shared home directory to bring small personal files between instances. It's not a universal $storage solution for everything, and I'd be willing to bet the majority of our NFS I/O is for data that isn't taking advantage of the sharing aspect anyways (or doesn't need to), and could theoretically be on local ephemeral storage, possibly with backups.