[gentoo-user] NFS tutorial for the brain dead sysadmin?

[walt <w41ter@gmail.com>]

In this case, the brain dead sysadmin would be moi :)

For years I've been using NFS to share /usr/portage with all of the
gentoo machines on my LAN.

Problem:  occasionally it stops working for no apparent reason.

Example:  two days ago I updated two ~amd64 gentoo machines, both of
which have been mounting /usr/portage as NFS3 shares for at least a
year with no problems.

One machine worked normally after the update, the other was unable to
mount /usr/portage because rpc.statd wouldn't start correctly.

After two frustrating days I discovered that I had never enabled the
rpcbind.service on the "broken" machine.  So I enabled rpcbind, which
fixed the breakage.

So, why did the "broken" machine work normally for more than a year
without rpcbind until two days ago?  (I suppose because nfs-utils was
updated to 1.3.0 ?)

The real problem here is that I have no idea how NFS works, and each
new version is more complicated because the devs are solving problems
that I don't understand or even know about.

So, please, what's the best way to learn and understand NFS?

Thanks for any clues.