What utility can be used to monitor system performance over time?

The choice of utility for monitoring system performance over time is particularly well-suited for 'sar' (System Activity Report). This command is part of the sysstat package and is designed to collect and report system activity information over time. It gathers performance data regarding CPU usage, memory, I/O operations, and network activity, among other metrics, allowing administrators to analyze performance trends and identify potential issues.

What sets 'sar' apart from other utilities is its ability to log historical data. It can be configured to run at regular intervals, collecting statistics that can later be reviewed, which is essential for analyzing performance over long periods or during specific events.

In contrast, while 'top' and 'htop' provide real-time monitoring of system performance, they do not have built-in capabilities to log this information for analysis at a later date. They primarily focus on displaying the current state of the system, updating the information dynamically. 'vmstat', on the other hand, offers insights into memory and swap utilization as well as process counts but also lacks the long-term data logging functionality that 'sar' provides. Thus, 'sar' is the most appropriate choice for persistent monitoring of system performance over time.