I use Nagios to monitor my systems and occasionally get alerts that I had high memory utilization on some of my machines. But using
free -m, all I found was confusion.
Until recently, I thought the only way to free up the memory was to reboot the server. When it comes to how OS's manage their memory, it can be kind of unclear for some people.
free -m often don't seem to line up is because of the different states of memory. There are two states of used memory, inactive and active.
Active memory is memory that is being used by a particular process. Inactive memory is memory that was allocated to a process that is no longer running.
free -m do not differentiate between these two types of memory. This is why
free -m may show only 2% memory available. while
top may only show a few processes using 1 or 2%.
To better understand the differences between inactive and active memory, think of it this way. If you were to...Read More
It's been almost 3 years since PHP 7.0 was released. At that time, I quickly updated my servers. When I did that, I killed my old site by killing
mysql_*. I elected not to update that site, in favor of rebuilding.