A common job for a system administrator is to troubleshoot a Linux server to find out why it’s running slowly.
The following command will give you a great overview and should only take less than a minute to review.
uptime
The uptime command will, naturally, tell you the uptime of your server but will also give you the load averages. This will tell you how busy your server is and has been in the recent past.
dmesg | tail or journalctl -n 20
These commands will tell you if the system has recorded any information about any issues it is having.
vmstat 1
This command will tell you information about RAM and disk unsage. Take a look to review the amount of data going into disk and RAM. The iowait stat also tells you if disk contention is causing speed issues.
mpstat -P ALL 1
This will give you an idea of the work balance across the CPU cores.
pidstat 1
This will tell you what processes and users are using the CPU resources.
iostat 1
This tells you the disk I/O.
free -m
This will tell you the current memory usage and available free memory. The buff/cache and available lines will tell you how much memory your server has available.
sar -n DEV 1
This will tell you how much data is being received and transmitted from your server.
top
The top command is always a good idea to get an overall view of your system.