So I wrote my original RetroChallenge 2012 Summer Challenge proposal over a week ago and I’ve had a lot of time to think about the project since then. I have decided to modify my plan slightly, I think it’s an improvement and will make the cluster a truly innovative piece of hardware and software integration.
- The revised design will consist of 1x Intel Atom Mini-ITX motherboard (running NetBSD) plus 3 Raspberry Pi boards contained in a 1Ux500mm server chassis (that’s about a 500mm square footprint).
- SATA or MiniPCIe/SATA storage will be used on the Atom Motherboard to optimise I/O performance from the simulated storage devices.
- The TCP/IP networking will be setup thus:
- The Atom motherboard will (hopefully) have 2 Ethernet Ports. One will be wired into the internal network and one exposed to the outside world.
- The internal TCP/IP network will exist on it’s own subnet (I plan on using the 220.127.116.11 as it’s not commonly used)
- The network will be bridged in NetBSD on the Atom motherboard to allow DECnet packets to flow between the interfaces, effectively allowing DECnet traffic in and out of the cluster freely.
- The out-facing LAN interface on the Atom motherboard will be intended top be configured to the subnet of the user’s network, thus giving the entire cluster effectively 1 IP address.
- Terminal access to each Raspberry Pi SimH simulation will be provided via the Atom NetBSD OS.
- I plan on having the following nodes:
- Atom ITX board: VAX 3900 simulation with 8 RA92 (1.5GB) disk images. Responsible foe user records, user storage (each users default directory), also possibly FTP, FAL, LAT, MOP and DECnet file services to the outside world, web server (possibly allowing remote Notes access).
- Raspberry Pi 1: VAX 3900 simulation DEC Notes server (I love DEC Notes).
- Raspberry Pi 2: VAX 3900 simulation Disk-based Workstation
- Raspberry Pi 3: VAX 3900 simulation Diskless Workstation (possibly booted using a MOP image?)
- Each VAX simulation will run as a background process using GNU ‘screen’ to manage the session and allow it to be picked up and dropped without disrupting simulator functionality and will start with the host machine on boot.