20 Linux System Monitoring Tools Every SysAdmin Should Know

Need to monitor Linux server performance? Try these built-in command and a few add-on tools. Most Linux distributions are equipped with tons of monitoring. These tools provide metrics which can be used to get information about system activities. You can use these tools to find the possible causes of a performance problem. The commands discussed below are some of the most basic commands when it comes to system analysis and debugging server issues such as:

1. Finding out bottlenecks.
2. Disk (storage) bottlenecks.
3. CPU and memory bottlenecks.
4. Network bottlenecks.

1: top - Process Activity Command

The top program provides a dynamic real-time view of a running system i.e. actual process activity. By default, it displays the most CPU-intensive tasks running on the server and updates the list every five seconds.

2: vmstat - System Activity, Hardware and System Information

The command vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity.

# vmstat 3

procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
0  0      0 2540988 522188 5130400    0    0     2    32    4    2  4  1 96  0  0
1  0      0 2540988 522188 5130400    0    0     0   720 1199  665  1  0 99  0  0
0  0      0 2540956 522188 5130400    0    0     0     0 1151 1569  4  1 95  0  0
0  0      0 2540956 522188 5130500    0    0     0     6 1117  439  1  0 99  0  0
0  0      0 2540940 522188 5130512    0    0     0   536 1189  932  1  0 98  0  0
0  0      0 2538444 522188 5130588    0    0     0     0 1187 1417  4  1 96  0  0

Display Memory Utilization Slabinfo

# vmstat -m


Get Information About Active / Inactive Memory Pages

# vmstat -a




3: w - Find Out Who Is Logged on And What They Are Doing

w command displays information about the users currently on the machine, and their processes.

Sample Output:

17:58:47 up 5 days, 20:28,  2 users,  load average: 0.36, 0.26, 0.24
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
root     pts/0    10.1.3.145       14:55    5.00s  0.04s  0.02s vim /etc/resolv.conf
root     pts/1    10.1.3.145       17:43    0.00s  0.03s  0.00s w

4: uptime - Tell How Long The System Has Been Running

The uptime command can be used to see how long the server has been running. The current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes.

Output:

18:02:41 up 41 days, 23:42,  1 user,  load average: 0.00, 0.00, 0.00

1 can be considered as optimal load value. The load can change from
system to system. For a single CPU system 1 - 3 and SMP systems 6-10


load value might be acceptable.