Linux server performance monitoring
Along with website and services availability monitoring we provide Linux server performance monitoring. It includes:
- CPU usage monitoring
- memory monitoring (incl. swap usage)
- disk space usage monitoring
- bandwidth monitoring
- and load average monitoring.
Below short overview of each item is provided.
user: part of time CPU executes at the user level (application).
nice: part of time spent by CPU while executing at the user level with modified priority.
system: part of time spent by CPU at the kernel level.
iowait: part of time that the CPU was idle during which the system had an outstanding disk I/O request.
idle: part of time that the CPU was idle and the system did not have an outstanding disk I/O request.
One of the most important parameters is iowait. Unless it’s less than 20-30 your server performs well.
used: amount of occupied memory.
cached: disk caching. Used to make the system faster, actually it’s available for the application memory.
free: value of free memory.
If it appears confusing you could check nice explanation of Linux memory here.
Usually Linux uses swap memory only if there’s no free RAM memory. If your system’s swap usage is about 0 it means that there’s no lack of RAM memory problems. But if system uses swap a lot it could mean you might want to consider adding more memory or to optimize the applications.
Disk space usage
With serverbeep’s daemon you can choose what partitions space usage you want monitor.
Bandwidth monitoring is also one of our service features and probably one of the most critical for server monitoring.
The simplest definition:
In short it is the average sum of the number of processes waiting in the run-queue plus the number currently executing over 1, 5, and 15 minute time periods.
High load average is one the most common issues on Linux server. There could be a lot of sources but the most frequent are: Apache, MySQL and the applications code. Say, if your server LA is less than 10 you are safe.