I’ve written some other articles on this topic that you may find helpful: Examine the articles listed below to gain a further understanding of these memory-related issues and possible solutions.īe sure to m easure Linux system memory usage correctly. Each admin will have to answer those questions and others, case by case, or hire an expert to do so.ĭon’t be caught looking at “free” memory on your Linux system and jumping to conclusions because you should also consider available memory, buffers/caches, and other factors as outlined. These are the questions that resulted in the current state of those above servers. Can Server B be configured to use more buffers and cache?.During peak hours during swapping, does the “load average” stay below 12.00?.Should Server A be upgraded with more memory?.Is traffic/workload growth expected soon?.Should we downgrade memory on server B?.Is swapping slowing the performance of Server A?.When analyzing these systems, a sysadmin may ask a few pertinent questions:

Please note that the Linux Kernel will move memory pages least frequently used into swap space even if there is available memory. Note, that both of these servers have 12 CPU cores and swap to RAID 10 NVMe storage – thanks to. When you compare both systems, even though the load averages are similar (processing the same workloads), it is evident that one server is making use of almost 100% of its memory ( Server A) while the other server is wasting more than 50% of its memory ( Server B). Server B: After 153 days of uptime, 30GB of memory is still wasted (free).Ībove lies the difference between free vs. Server A: Has less than 1% free (wasted memory) and 13GB available memory. I also ran the uptime command to confirm that both systems have been online for some time. The result should look something like the two screenshots below. available memory in Linux, login to your server and enter the following command: free -h We are going to use the go-to command: free

With this in mind, let’s look at two 60GB memory Linux servers. In contrast, available memory is used memory that includes but is not limited to caches and buffers that can be freed without the performance penalty of using swap space. available memory in Linux is that free memory is not in use and sits there doing nothing. Available memory is then an estimation of how much memory is available for use without swapping. Once your applications/processes have launched, and considerable uptime has passed, this number should almost always be small.Īvailable memory is the amount of memory that is available for allocation to new or existing processes. For this reason, especially on servers, I like to consider free memory as wasted memory.

What exactly is free memory, and how is it different from available memory?įree memory is the amount of memory that is currently not used for anything.

Linux command monitor memory usage