Game Server RAM Allocation: Real Memory Requirements for Minecraft, Rust, Valheim, and ARK

RAM Is the First Number That Kills a Game Server

Every game server runs out of memory before it runs out of CPU. The reason is structural: Minecraft, Valheim, Rust, and ARK all hold the entire mutable world state in RAM, and a single runaway mod or a chunk-loading storm can consume the last gigabyte in seconds. Out-of-memory (OOM) kills do not produce a graceful error — they produce a killed process, a corrupted region file, and a player rollback.

This guide gives allocation numbers grounded in the JVM heap and native-memory behavior of the major dedicated server binaries, not vendor marketing minimums. If you are choosing hardware around these numbers, start with our main site overview of dedicated hosting.

The Two-Part Memory Model

For any server binary, total RAM use is: heap (world state + entities) + native (JVM/metadata, off-heap buffers, mod native code) + OS page cache headroom. Budget 15-25% of RAM for native and OS overhead before allocating heap. If you set a 12 GB heap on a 16 GB box and the JVM native footprint is 3.5 GB, the kernel OOM killer will end your evening.

Minecraft (Java Edition)

Profile	Heap (-Xmx)	Total RAM	Notes
Vanilla, 10 players	4 GB	6 GB	Aikar’s/Paper flags reduce GC pauses
Vanilla, 40 players	8-10 GB	12 GB	Add 200 MB per persistent loaded chunk region
Modpack (200+ mods), 15 players	10-12 GB	16 GB	Mods add native allocations outside heap
Large modpack, 60 players	16-20 GB	24-32 GB	Requires Paper/Folia tuning + pre-gen world

Never set the heap above 50% of physical RAM on a combined host. G1GC performs best with a heap between 8 and 24 GB; beyond that, pause times grow and a 40-player server starts stuttering on chunk generation.

Valheim, Rust, and ARK

Valheim — 2-4 GB for 10 players; 8 GB for 20+. The world file grows with explored terrain, so a heavily-explored 500-hour world can triple base memory use.
Rust — 8 GB minimum, 16 GB recommended for 100-200 players. Entity count (deployed structures) drives memory, not player count.
ARK: Survival Ascended — 16 GB minimum, 32 GB recommended. The heaviest mainstream dedicated server; dino and structure counts dominate.

Why “Enough RAM” Still Crashes

Three failure modes survive generous allocations:

Heap fragmentation under long uptime — a server running 30+ days with a variable entity load can fragment the heap and fail to allocate a large contiguous region even with free memory available. Restart on a schedule (weekly) or use ZGC.
Unbounded mod memory — a single mod that caches chunk data can add gigabytes with no warning. Monitor per-mod memory before blaming the hardware.
Swap as a slow poison — if the OS swaps game memory, tick time collapses from 5 ms to 200 ms before the crash. Disable swap or set vm.swappiness=1 and treat swap use as an alert, not normal behavior.

Monitoring the Right Metric

Watch native + heap combined against physical RAM, not heap against -Xmx. Alert at 80% of physical RAM with a 5-minute sustained window. For native binaries such as Rust and ARK, monitor RSS directly. Keep 20% headroom at all times — page cache is what keeps world saves fast, and starving it turns a 200 ms save into a 4-second stall.

Sizing the Host Around the Server

Game server memory requirements do not exist in isolation. The same 16 GB of RAM has to cover the game process, the OS, any control panel or monitoring agent, and page cache for world saves. On a host running a single game server with a control panel, budget 2-3 GB for the OS and panel before you size the game process at all.

This is why a “16 GB” plan intended for a modpack is usually wrong: 16 GB minus 2.5 GB OS overhead minus JVM native footprint leaves well under 12 GB of usable heap. If you also run a database for plugins, a web map, or a Discord bot on the same host, subtract more. On a dedicated or bare-metal host you control every gigabyte; on shared infrastructure the ceiling is fixed and you cannot burst memory the way you can burst CPU.

Memory Speed and NUMA on Multi-Socket Hosts

For single-server game workloads, memory bandwidth rarely becomes the bottleneck — latency does. Where NUMA does matter is on dual-socket bare metal running multiple game instances. If an instance’s threads span both sockets, cross-socket memory access adds 30-60 ns of latency per access, which shows up as tick jitter. Pin each game instance to a single socket using numactl --cpunodebind and --membind. On most single-instance community servers this is unnecessary, but a hosting network running six instances per box should always configure it.

Allocation Cheat Sheet

Server	Players	Recommended RAM
Paper/Vanilla Minecraft	10-40	12 GB
Minecraft modpack	15-60	24 GB
Valheim	10-20	8 GB
Rust	100-200	16 GB
ARK: Survival Ascended	20-70	32 GB

Buy the RAM tier one step above your measured peak, not your average. Memory is the cheapest insurance against a corrupted world save, and it is the resource you can never burst on demand. For spec-and-price context across bare-metal options, see the hardware comparison on our main site.