Get the Offline ArchiveFree lifetime updates

Server Deployment

5 min read

Deploying servers means choosing which services the settlement runs, on which machines, with what power and with what written down. Start with name lookup, automatic addressing and a web server for the shared library, then add mail and file sharing; run them on one reliable machine at first, protect its power, mirror its disks and keep a second copy of the data on another machine. Every server is a salvaged computer that will eventually fail, so the plan is really a recovery plan: installation media, configuration and data kept somewhere other than the machine that uses them.

Part of Networking

Deciding what servers a settlement runs, where, on what power, and how to keep them recoverable.

A Server Is A Salvaged Computer Doing One Job Reliably

A server is not special hardware; it is any computer left running to answer other machines. The carrier Internet Infrastructure gives the minimum set of services: DNS for names, DHCP for addresses, HTTP for sharing knowledge, and SMTP and IMAP for mail, with file sharing as a fifth. Resource Sharing explains why these are worth running: they spread the cost of scarce hardware across everyone and are themselves shared resources.

What changes after a collapse is not the software but the supply. There is no one to buy a replacement from, no repository to fetch a package from, and no warranty. The right question for each service is therefore not “does it work” but “can we rebuild it from what we hold, and how long would that take?”

What You Need

  • One computer to start with, tested and with a disk you trust (Network Hardware covers testing)
  • Protected power — the carrier asks for a UPS (battery backup) on critical infrastructure, and Star Topology puts surge protection and a UPS in every wiring closet
  • A locked room — the carrier says to keep servers and switches in a locked, climate-controlled room
  • A second machine for copies and some offline media
  • Installation media and the packages you need, held offline — see Linux Server Setup
  • Paper — the configuration of every server, written by hand

Method: Bring Services Up Safely

Step 1: Fix the list of services Begin with the carrier’s minimum. Resist adding more; the carrier says each unnecessary service is an unmonitored attack surface and a maintenance burden.

Step 2: Choose how many machines One machine is easiest to build and the biggest single point of failure. Separating the router from the servers lets each be fixed alone (Network Hardware makes that point about consumer routers). A sensible start is one server and one router.

Step 3: Protect the data, not just the machine Mirror two disks (RAID 1, which Error Detection and Correction calls the most practical protection against a disk failure for a small system) and remember that Resource Sharing warns RAID is not a backup, because it preserves deletion and corruption as faithfully as good data.

Step 4: Back up to a second machine, and keep an offline copy The carrier’s table says daily automated backups to a second machine and weekly offline copies. File Transfer shows how to copy and verify.

Step 5: Write down everything Addresses, names, accounts and how each service was installed. The carrier also asks for diagrams on paper, not only digitally.

Worked Example: Sizing Storage For A Settlement

Assume 50 users (an assumption for the example). Shared Resources gives typical use of 5 GB per user and suggests a quota of 20 GB, which catches runaway processes without touching normal use.

Typical total: 50 x 5 = 250 GB. If every user hit the quota: 50 x 20 = 1,000 GB. A quota is a limit, not a reservation, so the disk needs to hold the typical total with room to grow, not the quota total. A backup on a second machine needs at least the same 250 GB, and the offline copy needs another 250 GB. Three copies of 250 GB is 3 x 250 = 750 GB of storage in all, before growth.

Common Mistakes

  • A single copy of anything important — a failed disk is permanent loss
  • Services that depend on a download — if the only source of the software is a mirror that no longer exists, the service cannot be rebuilt
  • Running a server on an unprotected supply — a brownout can corrupt a disk
  • Starting with the most ambitious service — a mail server before name lookup is a mail server that cannot find anyone

Safety

Salvaged power supplies and battery backups

A computer power supply holds charge after it is unplugged and contains mains voltage; do not open one. A UPS contains batteries that can deliver very high current and, if they are lead-acid, give off hydrogen when charging, so keep the room ventilated and keep metal tools off the terminals. See Electrical Safety. Keep a fire extinguisher suitable for electrical equipment at the door of the machine room.

What’s Next