If you are using a repository with the Berkeley DB back end (default for repositories created with Subversion 1.0 and 1. 1, not the default thereafter), we recommend not storing the repository on a remote filesystem (for example, NFS).
While Berkeley DB databases and log files can be stored on remote filesystems, the Berkeley DB shared region files cannot be stored on a remote filesystem. So the repository may be safely accessed by only a single filesystem client, and not all Subversion functionality will be available to even that one client.
If you are using the FSFS repository back end, then storing the repository on a modern NFS server (i.e., one that supports locking) should be fine.
Working copies can be stored on NFS (one common scenario is when your home directory is on an NFS server). On Linux NFS servers, due to the volume of renames used internally in Subversion when checking out files, some users have reported that subtree checking should be disabled (it's enabled by default). Please see NFS Howto Server Guide and exports for more information on how to disable subtree checking.