Current as of 15 August 2012
My master backend is connected to an iSCSI storage array. The recordings are stored in a nine-terabyte, RAID-5 array. A decade's worth of recordings takes up a lot of space! My first recording was an episode of Coronation Street on 15 September 2004.
I also have an NFS server connected to the same storage array. This NFS server stores my personal files along with my other media (e.g music, videos, RSS feeds) in a 2 1/2-terabyte, RAID-5 array.
I recently switched from Comcast to DirecTV, and I could not be happier. I am using SHEF (an HTTP interface) for channel changing and it works flawlessly. Comcast NEVER looked as good as DirecTV does. The picture quality is absolutely phenomenal. And my bill is one-third what it was. Never going back to cable television again. Don't know why I didn't switch sooner.
My original master backend, which I had used since I first started with MythTV, was an old machine with a Sempron 2300+ CPU and 512 MB of RAM. It had two Hauppauge PVR-250 cards connected directly to my cable feed. This machine ran KnoppMyth R5.5.
Despite its very humble configuration, this machine was able to record two feeds at once with absolutely no problems, even when it was using direct-attached storage in its many prior lives. It also was able to transcode from MPEG-2 to Xvid in "real time" (i.e. 30 fps). It had served me incredibly well over the course of six years.
About two years ago, I virtualized my master backend. It is running inside of a Xen virtual machine and runs Debian (Debian "Squeeze" 6.0).
My master backend basically is used for my archive. Old recordings are moved from slave backends to the master backend on a regular basis.
My slave backend is the machine that actually does all of the recording. It is connected to two DirecTV H21 receivers - through Hauppauge HD-PVRs for recording, and with channel changing via SHEF. The machine records to local hard drives. Recordings more than seven days old are shipped off to the archive automatically.
I have tried many different hardware combinations for my frontends. I was a big fan of the Via Epia MII-10000 for the longest time, and used them in my frontends for about five years. With the advent of HDTV, the Epia M series simply could not keep up.
I used Asus Eee Box PCs for a little while, and I really liked them. I since have settled on Zotac ZBOXes for my frontends. They have very similar specifications as the Eee Box PCs, but are much easier to service (by design). In particular, my frontends are Zotac ZBOX HD-ID33BR-U with built-in BluRay drives.