What is the worst part about working in the System administration sector?

Real Worst part? Things change more rapidly than any other field.
One really have to be on his toes to learn new technologies.

Well Being an System Administrator means taking blame for everyone's mistakes: Networking, Programming, Quality, Security.
You need to know them all to cover your work to the point.
and always do backups on your own with the standard backups that are using in your company.
Oh yea expect the night calls anytime.

be ready to have argent phone calls at1 -2-3 AM.

hard disk replacement and reducing a File System

The efficiency of a modern enterprise now relies crucially on the proper functioning of its IT infrastructure (application servers, databases, web services, cloud computing, etc.).
The administration and maintenance of large enterprise computing systems pose problems more complex in terms of design and efficiency.
The Administration MBA Information Systems as experts able to meet this challenge.
  The argument "security" is the problem of a system administrator.