Mounting CentOS 6 NFS on a CentOS 4 Client

I have a CentOS 6 machine that exports NFS shares for various virtual machines to mount and use as needed (mostly to build code on various platforms and architectures).

One of the problem machines is a CentOS 4 VM that mounts the CentOS 6 NFS share upon boot. I fought with this damn VM for an hour before the simple solution hit me. CentOS 4 uses an older version of NFS (nfs?) than CentOS 6 does by default (nfs4).

Here is the relevant line in the CentOS 6 NFS server machine's /etc/exports file:
/home/sm *(ro,insecure,no_root_squash)

Here is the CentOS 4 NFS client VM's /etc/fstab file (the one that does not work):
mndevtest:/home/sm /mnt/smhome nfs defaults 0 0

And here is the CentOS 4 NFS client VM's /etc/fstab file (the one that does work):
mndevtest:/home/sm /mnt/smhome nfs4 defaults 0 0

Literally a ONE CHARACTER change fixed it. I love computers. /s

Fixing the Reboot Command

Somewhere along the line, my Ubuntu 14.04.3 installation (on a Zotac Z-Box) stopped accepting any typed reboot command. It seems to have happened after I removed gnome-power-manager; but even though I reinstalled it, the reboot command still wouldn't work. I'm not sure whether that was the cause, but I think it has a high chance. Anyway, thanks to http://michalorman.com/2013/10/fix-ubuntu-freeze-during-restart/, this little trick worked...

Edit grub's default configuration:
# vim /etc/default/grub

Add the following to the GRUB_CMDLINE_LINUX_DEFAULT string:
reboot=warm,cold,bios,smp,triple,kbd,acpi,efi,pci,force

The kernel will attempt each type of reboot in that order, until one works.

After saving that file, be sure to run the following command to enact your changes:
# update-grub

Reboot your machine, and the reboot command should now work.