A Rivendell workstation with Jack2 and Netjack to work with a server needs a reliable motherboard with an X64 processor with two to four cores, Several Gigs (3?) of Memory, and if to be used with a server for audio storage and database, probably 120 Gigs of SSD. If the machine will be in a playout or editing environment, an SSD is important for fast boot and fast loading of applications. The $50 a little SSD costs is well worth it. An additional hard drive is needed to keep keep work files in the /home folder. If you have a good server, you don’t need a big hard drive unless you want to duplicate the library and database on the workstation (this is tricky because they need to be kept sync’ed)
If you work with a server, you need a good quality Gigabit network card which you will set up for STATIC ADDRESSING.
You need a good sound card fully rated for ALSA compatibility. I have used M-Audio hardware with good results, particularly the Delta 1010 cards and the all of the 17xx cards work well too. Ubuntu studio 14.04 has also learned to play nice with M-Audio Fast Track 8R USB rack mounted box. (earlier versions did not) Rivendell loves the Audio Sciences cards, but they are pricey.
If the workstation is in the studio, you also want high volume LOW NOISE fans. Bigger cabinets seem to have quieter fans because they use larger 120 mm fans that move more air with slower blades. You should also use a good quality power supply and UPS. The UPS should be connected to the computer USB for graceful shutdown when the power goes out, and stays out.
The current version of Rivendell playout has a fixed window size so don’t go crazy on resolution or the control window will be too small. (I have heard that this is likely to change in the next major revision). Your video card does not need to be anything special, motherboard cards work fine. rdAirplay will work with a touchscreen, and there are many that work with Ubuntu-Studio, but not all. Your touchscreen mileage may vary. You are looking for high reliability, not blazing performance. Do not overclock.
Rivendell works with audio switchers such as the Broadcast Tools SS 8.2, and with digital IO cards that talk by RS-232 serial ports. It would be nice if the motherboard had an RS-232 port, but a high quality USB-RS-232 converter will work. There are cheap converters that won’t work because they need a special driver that might not be available in Linux. The machines that will be running RdCatch and RdAirplay will need this if you need these outputs to switch satellite receivers and such. (Audio switchers may be unnecessary if you have enough inputs and outputs on your soundcards when running Jack2.)
A server for Rivendell should have similar computing performance to the workstation, and should have a reasonable amount of memory on a multi-processor X64 chip, with four or more gigs of memory. Hard drives should start with a 128 Gig SSD for the operating system, and about 2 TB or more of high quality hard drives for audio and database.
You should have two or three Gigabyte Ethernet ports on this machine.
It theoretically could be a “headless” machine, but some of the audio applications just really need GUI interfaces. Sharing a monitor, mouse and keyboard with a KVM switch with another machine (such as a standby server) would be useful. Be careful that the KVM switch and the motherboard have the same mouse and keyboard connectors. USB to DIN adapters generally don’t work on KVM switches. No fancy video card is needed.
If this will be the “master control for audio” it will need a good ALSA compatible sound card with as many output channels as you will have outputs. The server should have at least a 2 TB USB removable drive or a Network Attached Storage device for backups. You may have trouble finding servers that are quiet enough for the average station. If you will be running the servers in a server closet, I recommend recently pulled 1U to 4u servers with dual power supplies. They will, however, be much too noisy for an office or studio environment. You probably can’t afford them new, but used are inexpensive, just make sure you get multiprocessor X64 machines with enough memory
Your “music” ethernet network should be built with good Cat6 cables – any that go through the ceilings or floors should be ‘plenum’ rated. Use high quality gigabit switches. You probably can do without managed switches unless you have a lot of workstations, and then we have to tune things that I haven’t had to do yet.
It is possible to set up a server standby system for Rivendell, where you have two identical servers for Rivendell and the audio store or the database are kept up to date on both. This way a failure will not put you off the air until a new server can be configured. Similarly, you should keep your workstations as close to identical as possible so you can switch over quickly in the case of an equipment failure.
If you are doing hot standby servers, it would make sense to have two independent UPS systems – one for each server, and a ups for each workstation. The idea is “no single point of failure”! This is where the use of a real router (not bestbuy specials, but microtik or cisco) become important.
When you set up Ubuntu studio on these machines make sure you choose to add .mp3 codec and use LVM. The account you use to setup will be the main “SUDOER” account. Use a real password and require it to be entered. It might make sense to encrypt the main account’s /home folder.
The server might be called on to do more than switch audio, serve the databases, and stream. You may want to run the station’s phone system using freeswitch, or at least the phone interfaces to the studio. It may make sense to put these into separate “boxes” using Oricle’s Virtualbox or the more sophisticated OpenStack. If you are thinking about using openstack, you will need at least one processor per “node” so a six or eight processor computer for the server makes sense, along with more memory, as each node has its “own” memory.