So, I am using Zabbix to monitor my server. At / file system I have 63 GB free. So I wanted to fake a huge file on that directory to see if the Zabbix graphs would correctly show that the used space had increased. So I ran this :
cd / && sudo fallocate -l 50000000000 archivogrande.txt
Which is working correctly and creating a file of approximately 50 GB. Unfortunately, Zabbix graph does not get updated. I can still see that there is 63 Gb free when actually it should say 17. The graph is getting updated every 10 seconds by the way.
So, my question is, regardless of what Zabbix might or might not doing wrong here, is my command actually doing what I expected? Would monitoring software correctly see the increase in used space, even if its not a "real" file?
to answer your question - yes
fallocatecommand is actually doing what you think it is - you are occupying about ~50 GB of space by the file you created.Your zabbix-agent binary should be able to detect the space has decreased and alert you that free space is bellow 10% if you're using the correct item and trigger and the monitoring is working OK.
Since this is not the case please verify:
look at the logs of server and agent to figure out what's wrong.