Implementing NFSv3 in Userspace: Design and Challenges

NFS in usermode is an uncommon challenge, one which necessitates unique design features not present in most UNIX implementations. EMC Isilon’s NFS team has been tasked with moving the kernel-based NFS server previously implemented in OneFS with one in userspace in order to take advantage of a new protocol-agnostic access auditing framework. This talk will serve as a postmortem discussion and case study of EMC Isilon’s new usermode NFSv3 server. We will discuss some of the challenges we encountered while redesigning the server for its new environment, future-proofing our design, and maintaining common code with SMB, NFSv4, and other protocols.

Learning Objectives

Advantages of user mode over kernel mode for Isilon in particular, and clustered storage in general
Userland challenges, including operation transactions, filehandle translation, and the RPC model
Design considerations inherent in sharing code with SMB and NFSv4