Monitoring resource usage on your VPS is crucial for maintaining performance and stability. Here are some tools you can use to monitor CPU, RAM, disk, and other system resources:

### **1. **Built-in Tools

#### **For Linux:**

1. **`top`/`htop`:**

   - **Usage:** Provides a real-time view of CPU, RAM, and process usage.

   - **Command:** `top` or `htop` (install `htop` via `sudo apt install htop` for Ubuntu/Debian).

2. **`vmstat`:**

   - **Usage:** Displays information about system processes, memory, paging, block IO, traps, and CPU activity.

   - **Command:** `vmstat 1` (refresh every second).

3. **`iostat`:**

   - **Usage:** Provides information about CPU utilization and I/O statistics.

   - **Command:** `iostat -x 1` (for extended statistics every second).

4. **`free`:**

   - **Usage:** Shows memory usage including total, used, free, shared, and cached memory.

   - **Command:** `free -m` (in megabytes).

5. **`df`/`du`:**

   - **Usage:** Shows disk space usage.

   - **Command:** `df -h` (for human-readable format), `du -sh /path/to/directory` (for directory size).

#### **For Windows:**

1. **Task Manager:**

   - **Usage:** Provides a basic overview of CPU, RAM, disk, and network usage.

   - **Access:** Press `Ctrl + Shift + Esc` or right-click the taskbar and select "Task Manager."

2. **Performance Monitor:**

   - **Usage:** Offers detailed performance data and allows you to create custom monitoring reports.

   - **Access:** Search for "Performance Monitor" in the Start menu.

3. **Resource Monitor:**

   - **Usage:** Provides a detailed view of CPU, memory, disk, and network activity.

   - **Access:** Open Task Manager and go to the "Performance" tab, then click "Open Resource Monitor."

### **2. **Third-Party Monitoring Tools

#### **For Linux and Windows:**

1. **Nagios:**

   - **Usage:** A powerful monitoring system that can monitor various system resources, services, and applications.

   - **Website:** [Nagios](https://www.nagios.org/)

2. **Zabbix:**

   - **Usage:** Provides detailed monitoring and alerting for various system metrics and applications.

   - **Website:** [Zabbix](https://www.zabbix.com/)

3. **Prometheus with Grafana:**

   - **Usage:** Prometheus collects metrics and Grafana visualizes them, providing insights into system performance.

   - **Website:** [Prometheus](https://prometheus.io/) and [Grafana](https://grafana.com/)

4. **Netdata:**

   - **Usage:** Provides real-time monitoring and visualization of system metrics.

   - **Website:** [Netdata](https://www.netdata.cloud/)

5. **Datadog:**

   - **Usage:** Cloud-based monitoring service that provides comprehensive monitoring and analytics.

   - **Website:** [Datadog](https://www.datadoghq.com/)

6. **New Relic:**

   - **Usage:** Offers application performance monitoring and infrastructure monitoring.

   - **Website:** [New Relic](https://newrelic.com/)

7. **SolarWinds:**

   - **Usage:** Provides a range of network, server, and application monitoring tools.

   - **Website:** [SolarWinds](https://www.solarwinds.com/)

### **3. **Cloud Provider Tools**

Many VPS providers offer built-in monitoring tools in their control panels:

- **DigitalOcean Monitoring:** Provides metrics on CPU, RAM, and disk usage.

- **AWS CloudWatch:** Monitors AWS resources and applications, including custom metrics.

- **Google Cloud Monitoring:** Offers comprehensive monitoring solutions for Google Cloud resources.

### **Summary**

1. **Built-in Tools:** Use `top`, `htop`, `vmstat`, `iostat`, `free`, `df`, and `du` on Linux; Task Manager, Performance Monitor, and Resource Monitor on Windows.

2. **Third-Party Tools:** Consider Nagios, Zabbix, Prometheus with Grafana, Netdata, Datadog, New Relic, and SolarWinds for advanced monitoring.

3. **Cloud Provider Tools:** Utilize built-in monitoring features from your VPS provider like DigitalOcean Monitoring, AWS CloudWatch, or Google Cloud Monitoring.

By using these tools, you can effectively monitor and manage your VPS's resource usage, ensuring optimal performance and timely identification of potential issues.