NFS3 FAILOVER
=============

NFS3 Failover is part of big project were I was working during 2010 in order
to manage a large fleet of physical hosts. To keep some files in-sync with all
nodes in the system, I use NFS3 in read-only mode.

While the master nodes provides the content of that files, the slaves
nodes just mount the shared directory and read the data.

To keep the system scalable I use a number of masters per slaves,
that is, for example, 4 master nodes per 40 slaves nodes. Unfortunately
mainline version of nfs3 modules (sunrpc, actually) and mount binaries
do not support failover for NFS3 (NFS4 includes failover by design). In
order to enable this capability, we need to implement failover
functionality for nfs3 in kernel modules and moun options.

Most of the work was done by my colleage Manuel Sanmartín, I just
adapt these patches to run in modern linux versions and new mount
tools.

This repository contains submodules to patched kernel sources (linux/
directory) and nfs-utils patched sources (nfs-utils/ directory).

To install patched sources you need to recompile kernel and nfs-utils as
usual:

  cd linux/ && make menuconfig && make && make modules_install && make install
  cd nfs-utils/ && ./configure && make && make install