ATOP is an advanced interactive monitoring tool to analyze the load and hardware resources on a Linux system. It shows the CPU, Memory, Disk and Network resource usages. Atop gives the resource occupation on system level followed by the information of processes that have been active during the time interval (10 seconds default).

In an Atop window , various system activity reports can be generated by using different keys:
Key m : Memory consumption
Key d : Disk utilization
Key s : Scheduling information
Key v : Variable information
Key c : Command line
Key p : Accumulated per program
Key u : Accumulated per user
Key n : Network utilization

Installation

1. To install on Centos, depending on 32 or 64 bit you can choose rpm from “http://pkgs.repoforge.org/atop/”.

2. yum install atop

After installation you can use interactive atop commands from atop man page.

Logs

When atop is installed, a cronjob is activated to run a background incarnation of atop that writes compressed samples to a log file in raw format.
These log files can be found in the directory /var/log/atop. When the command “atop -r” is started, today’s log file will be shown. When specifying another date as argument, the concerning log file will be shown.
For example: To view log file corresponding to the date 23rd June 2012, you can use the following command:

[~]# atop -r 20120623

Advantages

Atop has some major advantages compared to other performance-monitors:

1. Resource consumption by all processes
It shows the resource-consumption by all processes that were active during the interval, so also the resource-consumption by those processes that have finished during the interval.

2. Utilization of all relevant resources
Shows system-level counters concerning cpu-, memory- and swap-utilization, however it also shows disk I/O and network utilization counters on system-level.

3. Permanent logging of resource utilization
It is able to store raw counter-data in a file (compressed) for long-term analysis on system- and process-level. By default the daily log files are preserved for 28 days .

4. Highlight critical resources
It is able to highlight resources that have (almost) reached a critical load by using colors for system statistics.

5. Accumulated process activity per user
For each interval it is able to accumulate the resource consumption for all processes per user.

6.Accumulated process activity per program
For each interval it is able to accumulate the resource consumption for all processes with the same name.

7. Disk and network activity per process
In combination with optional kernel patches it shows process-level counters concerning disk I/O and network activity.

The above is a very rough outline of the System Monitoring Tool (Atop) , if you have any questions, we would be happy to talk to you! 🙂

About the Author :

Saranya Soman works as a Software Engineer in Bobcares. She joined Bobcares in March 2011. She loves reading books and listening to music in her free time.

Blog edited by :

Arundhati Rath works as a Software Engineer in Bobcares. She joined Bobcares in June 2011. She loves listening to music in her free time.