## 3 Materials and Methods
### Metrics Analysis Through Dashboard  
The initial step involved analyzing metrics related to system components such as CPU, disks, network interfaces, memory, and WebDav performance. INFN-CNAF provided an interactive dashboard featuring visualizations of key metrics, enabling pattern and anomaly identification. While not all metrics from the database dump are displayed, the dashboard focuses on the most relevant ones. Metrics are categorized into three groups: general, detailed graph, and StoRM WebDAV metrics.  
* General metrics: The \"general\" group of metrics provides an overall view of the system's main components, offering insights into trends and variations affecting infrastructure performance. Key metrics include CPU usage details, such as user and system process times, idle time, and time spent on I/O operations, as well as network traffic metrics that monitor incoming and outgoing data and analyze traffic per interface. These metrics enable basic monitoring of the CPU's operational state, workload distribution, and network capacity, helping to identify potential issues like bottlenecks and fluctuations.  
Figure 1 is an example of the dashboard visualization related to CPU usage metrics.  
* Detailed metrics: This group includes metrics for monitoring system memory and load, offering detailed insights into resource usage and system performance. Metrics include load average, which tracks the average number of running or waiting processes across hosts, and various memory-related metrics such as memory used, memory cached, memory buffered, memory free, and memory swap used. These provide a clear view of RAM usage, cached and buffered data, available memory, and swap memory utilization. This group enables a comprehensive assessment of resource utilization and helps identify areas for optimization.  
In Figure 2, the section of the dashboard concerning the load average can be observed, which is a metric representing the average load within a system. It indicates the average number of processes running or waiting to be executed by the CPU, divided across the various available hosts.  
Figure 1: The CPU metrics section in the INFN-CNAF dashboard. The plot of the values related to CPU usage by user processes can be observed in green, while the plot related to CPU usage by system processes is shown in yellow. The violet plot represents the time the CPU remains idle, while the blue plot refers to the time the CPU spends executing processes that have been assigned a lower-than-normal priority, but it is not directly visible in the figure due to an overlap with the orange plot, that represents the CPU’s waiting time for I/O operations.  
* StoRM WebDAV metrics: This group focuses on monitoring the WebDAV service, providing insights into service performance and resource usage. Key metrics include HTTP request rate, reflecting the volume of client requests, and workload metrics such as active dispatches, thread pool size, and thread pool utilization, which together depict system processing capacity and thread usage. Error monitoring is supported by the 4 xx and 5 xx error rate metrics, identifying client- and server-side issues, respectively. JVM threads metrics offer details on active, blocked, and executable threads within the Java Virtual Machine. Data transfer performance is tracked via TPC (Third-PartyCopy) pull throughput, which measures data speed and volume, and TPC pull success/error, highlighting the success rate of server-to-server data transfers. These metrics provide a detailed view of WebDAV service health and efficiency.  
In Figure 3, the section of the dashboard related to the \"HTTP request rate\" can be observed. This metric measures the number of HTTP requests received within a given time interval, thus reflecting the rate at which clients make requests to the server via the HTTP protocol.