Systems administration is an area where experience often comes right after you need it. Every senior sysadmin has “war” stories about the day they deleted the wrong database or crashed the company network.
Here are the most common mistakes that almost every beginner sysadmin makes, divided into critical categories.
1. The “Schrödinger’s Backup”
The mistake isn’t forgetting to back up (although that happens), but rather blindly trusting that it works.
The Mistake: Setting up backups and never testing the restore.
The Reality: An untested backup doesn’t exist. You only discover that the .tar.gz file is corrupted or that the database dump was empty at the time of the disaster.
The Solution: Implement the 3-2-1 strategy and schedule monthly restore tests.
2. The “Silver Bullet” of chmod 777
When something doesn’t work due to permissions, beginners panic and “open the doors.”
The Error: Running chmod -R 777 /var/www/html to resolve a “Permission Denied” error.
The Danger: You have just allowed any malicious user or script on the system to read, edit, and execute files.
The Solution: Understand how owners (chown) and groups work. Grant only the minimum necessary permissions (Principle of Least Privilege).
3. The Root Addiction
It’s tempting to use the most powerful user for everything because “it works without complaining.”
The Mistake: Logging in via SSH directly as root or using the root user for everyday tasks.
The Danger: A wrong command (like a misdirected rm -rf) is catastrophic. Furthermore, there’s no audit trail of who made the change if everyone uses the same root account.
The Solution: Disable root login via SSH. Use sudo for temporary privilege elevation.
4. “I’ll test it quickly in Production”
Overconfidence is the mother of downtime.
The Mistake: Editing configuration files (nginx.conf, my.cnf, php.ini) directly on the production server without testing beforehand, or deploying on a Friday afternoon.
The Consequence: The service fails to restart due to a syntax error, and the site goes down during peak hours.
The Solution: Have a staging environment. If this is not possible, always use syntax testing commands (e.g., nginx -t, apachectl configtest) before restarting the service.
5. Ignore Disk Space and Logs
Full disks are silent causes of data corruption.
The Error: Not monitoring the growth of log files or not configuring logrotate.
The Danger: The disk fills up (100% usage). The database attempts to write, fails, and corrupts tables. The system crashes because it cannot write temporary files.
The Solution: Configure monitoring (Nagios, Zabbix (configure on a separate server), or simple bash scripts) and ensure that logrotate is active and compressing old logs.
6. Disabling Security Because It “Gets in the Way”
Beginner sysadmins often see security tools as obstacles, not allies.
The Mistake: Disabling the Firewall (iptables -F / ufw disable) the first time a connection is blocked, and forgetting to re-enable it.
The Solution: Learn how to configure the rules. There are tools like audit2allow that help create exceptions without disabling the entire SELinux protection.
7. Mental Documentation
“I’ll remember what this script does and why I changed this door.” (Narrator: He didn’t remember).
- The Mistake: Not documenting changes, custom configurations, or service passwords.
- The Consequence: Six months later, the server needs to be migrated and nobody knows how it was configured, or you go on vacation and your colleagues are left paralyzed.
- The Solution: Maintain an internal Wiki, use comments in configuration files, and ideally, start studying Infrastructure as Code (Ansible, Terraform) so that the code becomes the documentation.
Resumo da Sobrevivência
| Common Mistake | Correction Mantra |
| Untested backup | “If it doesn’t restore, it’s not a backup.” |
| Log in as Root | “Sudo is your friend.” |
| Edit in Production | “Friday is read-only day.” |
chmod 777 | “Minimum permission required.” |
| Ignore Logs | “The record will sell out someday.” |
Veja também:
Guia Completo do DirectAdmin para Administradores | Instalação, Segurança e Performance
Como testar a velocidade da internet do servidor linux com speedtest-cli
Como verificar no linux a velocidade de I/O do disco
Como instalar Engintron(NGINX) cPanel/WHM
In english:
Why Migrate Reseller Hosting to a VPS or Dedicated Server