NAS

Placing your digital media collection on a NAS has a number of benefits:

• High availability - Many NASes draw very little power when they are idle, so they can be left permanently switched on.  This means you wont have to wait for computer to boot before you can start streaming music
  
• Protects your digital media files - if the NAS has RAID capability (hard-drive redundancy), you are protected from failure of any one of the drives in your system.  (However, this is not a substitute for a proper back up solution.)
  

Additionally, some NASes are capbable of running a media server.  This relieves your computer of one more task, and increases availability of your audio.

References

http://nas-central.org/ has a great selection of information about NASes from various vendors.

QNAP TS409 Pro

This is Linn's recommended NAS. It comes pre-installed with Twonky Media Server, is easy to install and manage and has a good solid finish.

The "Pro" version has NFS support, making it suitable for integrating a DS and Akurate Music Server in the same system allowing both products to share the same storage.

QNAP's lower end products are also reasonable choices for DS companion. eg The QNAP TS209 is a good 2 bay NAS with Twonky pre-installed.

Netgear ReadyNAS NV+

Linn's other recommended NAS.  Solid construction, and a good reputation.  4 Bays, and an expandible RAID implementation (XRAID).  Twonky doesn't come pre-installed but an easy to use installation package is available from thier web site.

Lacie Mini Ethernet Disk

Summary Compatible with Linn DS products, comes with Twonky Media pre-installed, easy to set-up, but no RAID support.

DLink DNS 323

The DLink is a cheap NAS, with RAID 1 capability.  The drive has limited firmware out of the box, (the pre-installed UPnP server is not very good), but it can be upgraded to run Twonky Media Server.

Installation experience of Twonky is relatively straight-forward if you are prepared to follow the instructions to install "fun_plug", (http://wiki.dns323.info/howto:fun_plug) and the Twonky installation instructions (http://www.twonkyvision.com/Download/TwonkyMedia/TM4Technicians.html)
* 2 disk SATA
* RAID 0,1,JBOD
* Linux ("busybox") based
* DHCP
* pre-installed uPnP server (DLink custom)