What it is¶

atop shows system-wide and per-process resource use, like top, but it can also record data at intervals and replay it later. That makes it the tool for "what was happening at 03:12 last night?" Homepage: atoptool.nl. Background: Using atop for Linux server performance analysis.

Usage¶

sudo dnf install atop        # or apt-get install atop
sudo atop                    # live view

The service writes daily log files:

sudo systemctl enable --now atop
atop -r /var/log/atop/atop_20260920          # replay one day
atop -r /var/log/atop/atop_20260920 -b 03:00 -e 03:30    # only a time window

Inside the replay, t steps forward in time and T steps back. In live and replay views, m shows memory, d disk, n network per process (network per-process needs the netatop module), and c the full command line. Logging interval is set with LOGINTERVAL in /etc/default/atop (or /etc/sysconfig/atop).

Related: sysstat/sar for system-wide history, pcp for a fuller metrics framework.