Reduce memory usage of a Linux game server

A Linux game server that runs low on memory becomes unstable even before it is fully saturated: slower response times, processes killed by the kernel, restarts and disconnected players. This guide proposes a careful method to measure RAM, find the cause and reduce memory pressure without deleting files at random, whether the server runs on a cloud VPS, a virtual server, a private server or a dedicated machine.

Measure before acting

Start by observing the available memory, the cache and swap. A high "used" memory value is not necessarily a problem: Linux also uses RAM for the cache and can release it. The important signal is the actually available memory, its evolution over time and the presence of allocation errors.

Take several measurements during a normal period and then during a player peak. Note the time, the number of players, the process involved, the available memory, the CPU and the remaining storage space. This comparison avoids changing the server based on a single isolated moment. It also helps distinguish a memory problem from a processor, SSD storage or bandwidth problem.

Identify the responsible process

Use an observation tool such as top or htop to sort processes by memory consumption. For a Minecraft server, watch the Java process and the heap size. For a FiveM server, observe the main process and the resources that keep increasing. With Pterodactyl or another panel, also compare the limit applied to the server with its actual consumption in the control panel.

Consumption that keeps rising without coming back down may signal a memory leak, a misconfigured resource or a load that is gradually increasing. Do not conclude there is a leak from a single measurement: document several startup, connection and disconnection cycles. Also check the ancillary tasks, databases, web server and administration services accessible over SSH.

Reduce the application load

Start with the game's own settings. Remove unused plugins, mods or resources, disable unnecessary features and check the scheduled tasks. Make one change at a time, then observe the effects. A recent backup lets you roll back if a resource depends on a removed setting.

With Java, do not give all the RAM to the JVM: the system, the libraries, the logs and the other services also need memory. A limit that is too high can leave less headroom for the system and make an incident worse. Adjust the heap size gradually based on the actual load and the server's total memory.

The same caution applies to FiveM servers and to applications installed on a Linux VPS. A script that consumes a lot of CPU can also cause more waiting and give the impression of a RAM shortage. So measure memory, processor, processes and network simultaneously before changing the configuration.

Understanding swap and the OOM risk

Swap can provide a safety net to absorb a peak, but it is not a substitute for RAM. If the game server constantly swaps memory pages, performance can drop sharply. So check memory pressure and the frequency of swapping, rather than treating swap as a permanent solution.

When the kernel can no longer satisfy allocations, the Out Of Memory mechanism can kill a process. Look for the corresponding events in the system logs after an incident. An SSH connection lets you keep this access even if the game panel no longer responds. If the killed process is the game server, reduce the load first or increase the available memory headroom rather than masking the symptom.

Checking Pterodactyl limits

A container memory limit that is too low can cause a shutdown even though the VPS still has memory. Conversely, a limit that is too high can let one game server crowd out the other services. Check the limit, the consumption and the startup parameters in Pterodactyl, then test with a representative load.

If several servers share the same VPS, add up their theoretical ceilings and keep a reserve for the system. This overview is essential before modifying a single server. In a virtualization environment, also check the resources actually allocated to the virtual machine and the host's capacity.

Preserving administration and security

Do not disable the firewall, the logs or SSH protection to save a few megabytes. These services have an operational and security function. On Debian or Ubuntu, check the enabled services, log rotation and network rules with a documented method. A stable IP address, correct DNS and a backup SSH access make diagnosis easier, but do not fix an insufficient memory capacity.

Also avoid installing heavy monitoring tools on a small virtual server. Choose lightweight measurement and keep only the useful metrics: available RAM, swap, CPU, disk space, restarts and service status.

Choosing a coherent architecture

Virtualization brings flexibility, but a virtual server must have a resource envelope consistent with the game and the number of players. In a VPS plan or cloud hosting, look at RAM, processor, storage space, operating system and the headroom needed for ancillary services together. A dedicated physical server may be more relevant when several virtual servers regularly compete for the same resources.

Do not pick a plan based only on storage capacity or a promise of unlimited resources. The actually available memory, the CPU frequency, the backup policy and the ability to scale the plan are more useful for a game server. High availability does not replace a correctly sized application either: it concerns service continuity, not the removal of a memory overload.

Preventing a new saturation

Keep tracking available memory, swap, the number of players and restarts. Define an internal alert threshold before saturation and check the logs after every incident. Also schedule tested backups: a memory optimization does not protect data in case of a failure.

If the normal load durably exceeds the VPS capacity, the clean solution is to reduce the scope of the service or choose a plan with more resources. A hosting provider can point you toward a more suitable VPS or a dedicated server depending on the number of players, the CPU needed, the RAM, the storage and the bandwidth. Check out our Docker advice on a VPS, our Pterodactyl backup guide and the information on Linux VPS to frame your operation.

To go further, also check out our guide to hosting a Minecraft server, the Minecraft server page and our FiveM server optimization guide. If your priority is machine administration, our guide to securing a dedicated server completes this diagnosis.