Build Your Own NAS/Subversion/Web/Anything Micro-Server

So which NAS box? The hackability of the NSLU2 is well known, but it doesn't have any disk built-in. I wanted a single box that contained everything. I discovered that the Buffalo LinkStation has a thriving developer community, so I went that route. You can also get a Kuro Box which is basically an already-open LinkStation with no hard disk. I went for the LinkStation since it came with everything needed, and is trivial to hack without even opening the box.

Then, which LinkStation? They have the "standard" models (HD-HxxxLAN) and also gigabit Ethernet (HD-HGxxxLAN). I chose the latter since it's not much more expensive, and comes with faster CPU and more memory. It turns out that some people have had trouble with re-flashing firmware on the 300GB model I bought, but fortunately I didn't run into this. Also fortunately, Buffalo replaced the LinkStations for people whose firmware update failed.

After buying the LinkStation, basic setup is trivial. Plug it in, turn it on, and it just works. Beautiful. The stock firmware provides SMB (Windows) and AppleTalk file serving, but the AppleTalk is down-rev and may not be useful (more on that later). I'd suggest creating a user account through their web interface at this point.

Hacking the LinkStation

You'll need a Windows machine for this part. Grab the OpenLink firmware, selecting the "HG" firmware if you gave a gigabit model. Follow the included directions, and about 5 minutes later you're done. It's really that easy. Now you have telnet and SSH access to your LinkStation.

The next step is installing the developer tools. Grab those, again selecting the HG tools for the gigabit model if necessary. Read the short document which tells you how to run the installer script, and you're done.

At this point you can install other pre-built packages from the Wiki or build your own from source.

Hard Drive Layout

The LinkStation has three partitions on its disk: one for swap and two for files. From "df":

Filesystem    1k-blocks      Used Available Use% Mounted on
/dev/hda1        373359    272459     81624  77% /
/dev/ram0         14521       214     13557   2% /mnt2/ram
/dev/hda3     306690228  15124600 291565628   5% /mnt

The vast majority of the disk is mounted at /mnt, and this is where all user files are stored. When you install new applications on the LinkStation they'll usually go in /usr or /usr/local by default, and this can fill up the hda1 partition if you're not careful. The easiest solution is to create a /mnt/local directory and then make /usr/local a symbolic link over to that, like so:

/usr# cp -r local /mnt/.
/usr# mv local local-bak
/usr# ln -s /mnt/local local
/usr# ls -l
(...)
lrwxrwxrwx   1 root  root  10 Mar 29 01:35 local -> /mnt/local
(...)
/usr# rm -rf local-bak  <- only when you're sure

Serving Mac Files the Right Way

Most people use SMB to connect their Mac and LinkStation (example here), but this has two problems:

1. Resource forks are lost.
2. Valid file names on Mac filesystems may not be valid over SMB.

Resource forks are a hold-over from pre-OS-X days and are mostly gone, but if you're got a bunch of expensive fonts around from those days, you need to preserve their resource forks or they'll be toast.

The file name problem bit me halfway through a huge file copy; there was a file with a percent sign in it, and SMB choked. Arrgh.

The AppleTalk file server (AFP) included with the LinkStation is an older version which has its own limitations (e.g. 31 character file name max), so that won't work. Go get the latest 2.x Netatalk source and copy it over to your LinkStation. Switch over to the directory containing the Netatalk source code. (Note that the LS's user directories, as configured through their web interface, are mounted under /mnt.)

There's one configuration change you need to make manually because the LinkStation doesn't use a shadow password file. Here are the build commands:

./configure --without-shadow
make
sudo make install

This will build and install under /usr/local. Now to configure Netatalk. If you're just using OS X machines, you can stick to TCP with strong authentication. Edit /usr/local/etc/netatalk/afpd.conf and add:

- -tcp -uamlist uams_dhx.so

(Yes, that's a leading dash by itself.) One last step to make LS users' home directories accessible: you need to edit /etc/passwd, and change the part right before ":/bin/bash" to match the correct directory. In my case, it looks like this:

Josh:mJdgd6zRFxXHo:101:1000::/mnt/josh:/bin/bash

Now you can start the AFP server:

/usr/local/bin/afpd

To get this new afpd to start at boot, you can edit the /etc/init.d/atalk script, or make a simplified version just for afpd. I'll discuss the latter technique in the Subversion section -- just replace "svnserve" with "afpd."

Revision Control

The term "revision control" (aka "version control" or "source code management") isn't well-known outside programmer geek circles, but it's an extremely useful technique for tracking changes to files. With a good program like Subversion you can archive both text and binary files with equal efficiency. It's also a great way to synchronize sets of files between machines while maintaining complete history -- you can literally "rewind" a copy to any previous version if needed.

I can't do proper justice to the benefits of revision control here; if you're interested, go buy the Subversion book or read it online.

The process of building a Subversion server on the LinkStation is a piece of cake: just copy the source into your user directory, and build. It builds and installs flawlessly. Run "svnserve -d" and you're ready to go.

There are a bunch of ways to access Subversion, including HTTP, SSH tunneling, and just raw Subversion protocol. Since I'm running this on my own private network, I just went with the raw protocol, which is what svnserve provides.

Starting Subversion (And Other Stuff) at Boot

The LinkStation uses normal Linux startup scripts, with only a few minor twists. Here's a simple startup script I used for Subversion:

#! /bin/sh
# ( saved on disk as /etc/init.d/svnserve )
start()
{
  echo 'Start services: svnserve'
  /usr/local/bin/svnserve -d
  /usr/bin/logger -t linkstation -p user.info -i 'Started svnserve'
}

stop()
{
  echo 'Stop services: svnserve'
  /sbin/killall "/usr/local/bin/svnserve" > /dev/null 2>&1
  /usr/bin/logger -t linkstation -p user.info -i 'Stopped svnserve'
}

case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    restart)
        stop
        start
        ;;
    *)
        echo "usage: $0 {start|stop}"
        exit 1
        ;;
esac

Save this on disk as /etc/init.d/svnserve. The next step is creating a few symbolic links so it's run at the right time during startup/shutdown. Here are the commands:

/etc/rc.d/rc2.d# cd /etc/rc.d/rc2.d/
/etc/rc.d/rc2.d# ln -s ../init.d/svnserve S90svnserve
/etc/rc.d/rc2.d# cd /etc/rc.d/rc0.d/
/etc/rc.d/rc0.d# ln -s ../init.d/svnserve K90svnserve
/etc/rc.d/rc0.d# cd /etc/rc.d/rc6.d/
/etc/rc.d/rc6.d# ln -s ../init.d/svnserve K90svnserve

Note that the LinkStation appears to only enter run level 2, not 3 as I'd expect.

And So On And So On...

You can make the LinkStation with OpenLink firmware into anything you want. So far everything I've experimented with has worked, sometimes right off the bat, other times requiring just a few tweaks. Even better, all the stock features still work, too. It's a great little box, and assuming you're cool with the command line and some Linux sysadmin foo, it's easy to customize to your heart's content.