General System Administration Overview

Classification of Systems:

Small sites have 1 - 10 machines, all running the same OS. Usually the administrator of a small site has only about 20 users. Usually there is only one administrator for a small site.

Medium sites have up to 100 machines, and may be running up to 3 different OSs. The administrator usually has about 100 users. Medium sites may have more that one administrator, either specializing in different operating systems or sharing general system administrator duties.

Large sites have over 100 computers, multiple operating systems, and over 100 users. At a large site, there will be a hierarchy of administration, with the lead or senior System Administrator responsible for all of the systems and assigning duties to one or more assistant administrators.

System Administration Skills:

System administration skills can be classified in four general levels. The links below discuss the required skills, desired skills, and responsibilities of each of those levels. Following the levels are some general thoughts on system administration in general.

Novice   Junior   Intermediate/advanced   Senior   Some thoughts on System Administration.

Novice System Administrator:


Junior System Administrator:


Intermediate/Advanced System Administrator


Senior System Administrator:


Finally, some important thoughts for system Administrators:

  1. Never do something you can't undo.
  2. Always check the backups, never assume they are working. Make sure you can restore from them, too.
  3. Write down what you did, even if you know you will never forget it, you will.
  4. If you do it more than once, write a script.
  5. Get to know your users before there is a problem, then when there is, they will know who you are and maybe have a little understanding.
  6. Remember you are performing a service for your users, you don't own the system, you just get to play with it.
  7. Check your backups.
  8. Never stop learning, there is always something you should know to make your job easier and your system more stable and secure.
  9. Check your backups, again.