Storage for blogs.dir

We need to somehow increase the storage for our wordpress blogs.dir. We have an external space where we can put stuff. Is there any way to set Wordpress so that it automatically puts all new blogs into another directory besides blogs.dir?

Or is there a better way to do this as our blog usage increases? Someone I recently talked to suggested adding a NFS mount between the VM server where our site is currently, and the storage space and restrict the traffic with IP tables. Then I might be able to set up an alias for the blogs.dir directory.

I'm not sure if that would work, or if there is something I need to do to wordpress to help it accept that. Any help you can provide would be appreciated.