DayZ server RAM: players, mods and economy

A DayZ server needs 4 to 6 GB of memory for a private group of ten to twenty on vanilla, 6 to 8 GB for the common 30 to 40-slot public server, 8 to 10 GB for a busy 40 to 60-slot vanilla server, and 10 to 12 GB for a heavily modded server with Expansion-scale mods, traders and AI. Memory grows with the mod list and with what persists on the map far more than with the player count: a 30-slot server carrying a large mod pack uses more than a 60-slot vanilla one. The resource that usually runs out first on DayZ is not memory at all but server FPS - one busy core - so prove which one you are short of before buying more of either.

What a DayZ server holds in memory#

DayZ's server simulates a 225 square kilometre map (Chernarus; Livonia is smaller) with a persistent economy. Its memory has four large parts.

• The map and engine floor. Terrain, buildings, the navigation data for infected and animals, and the engine itself. This is paid before anyone joins and depends on the map.
• The central economy. Every item that exists on the map is an object. The economy's job is to keep the number of each item type near its target, so a server with the vanilla types.xml holds tens of thousands of items at any moment - in buildings, on infected, on the ground, in players' inventories.
• Persistent objects. Tents, barrels, crates, base-building walls and gates, buried stashes and vehicles survive restarts through the persistence system. Everything inside them persists too. This is the part that grows over the life of a server.
• Mods. Every mod's scripts, configs and assets loaded into the server, and every item they add to the economy.

Players themselves cost comparatively little: their character, inventory and network state. What they cost indirectly is everything they build, hoard and leave lying around.

RAM by slots and mod list#

How to read it:

• Mods move you down the table faster than slots. A server running Expansion with its market, vehicles and AI modules, plus base-building and weapon packs, is a different machine from a vanilla server with the same slot count.
• Age moves you down too. A server that never wipes persistent storage accumulates bases and stashes, and their contents. A server three months into a wipe uses noticeably more than it did in week one.
• The CPU column matters as much as the RAM column. DayZ's simulation runs on a main thread. A 60-slot server is limited by server FPS long before it runs out of memory.

The DayZ server and mods guide uses the same figures and covers the install end to end.

The central economy is a memory setting#

DayZ's loot is controlled by the central economy files in the mission folder, mpmissions/dayzOffline.chernarusplus/ for vanilla Chernarus. Two of them set the numbers that matter for memory.

types.xml

Each item type has a target count (nominal), a minimum (min), a lifetime in seconds before an untouched item despawns, and a restock time:

<type name="AKM">    <nominal>8</nominal>    <lifetime>14400</lifetime>    <restock>0</restock>    <min>4</min>    <quantmin>-1</quantmin>    <quantmax>-1</quantmax>    <cost>100</cost></type>

The sum of nominal across every type is roughly how many items the economy tries to keep in the world. Doubling loot by multiplying nominals - a very common change on community servers - roughly doubles that part of memory, and adds CPU for the economy to manage it. Long lifetime values mean dropped and abandoned items stay longer. Mods that add weapons and gear add their own entries, and some mod packs ship generous nominals. types.xml and the loot economy explains every field.

globals.xml

Global caps and cleanup timers live in db/globals.xml. These are the memory-relevant ones:

Raising ZombieMaxCount for a harder server is common and costs memory and CPU in proportion. Lengthening cleanup lifetimes keeps bodies and ruined gear on the map longer, and on a busy PvP server that is hundreds of extra objects with full inventories. Check the values in your own file; mission files are updated with the game and some community missions change them.

Persistence: the part that grows#

Persistent storage lives in the mission folder's storage_1 directory (the number is the instanceId in serverDZ.cfg). Every tent, barrel, wall, gate, buried stash and vehicle is written there and loaded on every start, with its contents.

That gives DayZ the same slow climb as any base-building survival game:

• Week one is mostly the economy and the map floor.
• Month two adds every base on the map, every stash nobody remembers burying and every vehicle someone parked in a barn.
• Abandoned bases do not leave by themselves unless territory flags and their refresh rules are in play. On vanilla, a flag that is not refreshed eventually lets the base decay; on servers where flags are not used, persistent items rely on their own lifetimes.

A full persistence wipe resets all of it and is usually done with a map update or on a fixed schedule. DayZ server wipes and persistence covers what a partial wipe can remove and what a full wipe removes.

Proving it with the server's own logs#

DayZ can log its own memory and FPS to the server's .RPT file, which is the easiest way to get real numbers over a whole session. Add these to serverDZ.cfg:

logAverageFps = 60;logMemory = 60;logPlayers = 60;

Each value is an interval in seconds. With these set, the RPT log gains periodic lines with the average server FPS, the memory in use and the player count. Leave it running through a full restart cycle on a busy evening and you have exactly the data the sizing decision needs.

What to look for:

1. Memory across the cycle. It rises from the start as the economy fills and players spread out. If it is within about 10% of your limit before the next scheduled restart, you are short.
2. Server FPS under load. If FPS sags towards single digits as the server fills while memory has room to spare, the limit is CPU. More memory will not help; fewer infected, less loot, fewer AI and fewer heavy mods will.
3. The relationship between them. A server whose FPS falls steadily across a session, alongside rising memory, is the classic case for a shorter restart interval rather than a larger plan.

CPU or RAM: which one is holding your server back explains the general method, and game server CPU requirements covers what to do when it is the core.

Launch parameters that touch memory and CPU#

The DayZ server's launch line carries a few parameters worth knowing for sizing:

$ ./DayZServer -config=serverDZ.cfg -port=2302 -profiles=profiles \    -cpuCount=2 -limitFPS=60 -dologs -adminlog -freezecheck \    "-mod=@CF;@Dabs Framework;@DayZ-Expansion-Core"

What each of the relevant ones does:

• `-cpuCount` tells the engine how many cores to plan its worker threads around. Set it to match the cores you actually have; a value higher than the allocation only creates threads that compete with each other.
• `-limitFPS` caps the server's simulation frame rate. A cap stops the server burning CPU on frames nobody benefits from, which leaves headroom for the moments that need it.
• `-mod` and `-serverMod` list the mods loaded on both sides and on the server only. Every entry is memory at start; server-only mods (admin tools, logging, anti-cheat helpers) are no exception.
• `-freezecheck` makes the server stop itself if it hangs, which is better than a frozen process holding players for minutes.

On a panel-based host these are Startup variables rather than a line you type, and the mod list is usually its own field.

Mods: the biggest single variable#

DayZ's modding community is large and its big frameworks are substantial. The cost depends on what a mod does:

• Framework and admin mods - Community Framework, admin tools, logging - add modest memory and are often dependencies of everything else.
• Content packs - weapons, clothing, vehicles - add assets and economy entries. Each new item type that spawns is more objects on the map.
• Systems mods - Expansion's market, AI, quests, territories and vehicles; trader mods; base-building overhauls - add the most, because they add running systems and persistent state, not just items.

Expansion is modular, so a server can run its core and base-building modules without its AI and market, and the difference in memory and CPU is substantial. Install the modules you will actually use. The DayZ Expansion mod server guide covers the modules and their setup order.

A worked example: 40 slots with Expansion#

A community wants a 40-slot Chernarus server with Expansion's core, base-building, vehicles and market modules, a weapons pack, a clothing pack and a handful of admin and quality-of-life mods. Their loot is vanilla with weapons raised by half. Here is how to size it without guessing.

1. Start from the table. Forty slots vanilla is 6 to 8 GB. Expansion's systems and two content packs put it in the modded row, 10 to 12 GB. Begin with 10 GB and the expectation of moving up.
2. Measure the floor. Start the server with the full mod list, nobody connected, and logMemory on. Wait for the economy to finish spawning loot - this takes a while after start - and note the figure. That is the floor for this mod list and loot setting.
3. Measure a full evening. Let the server run a whole restart cycle at peak time with thirty-plus players. Note memory at the end of the cycle, just before the scheduled restart, and the lowest server FPS.
4. Decide. If the end-of-cycle figure is under about 85% of the plan and FPS stays healthy, the plan is right. If memory is close to the limit, either move up a tier or shorten the restart interval from four hours to three. If FPS sags while memory is fine, the answer is fewer AI, fewer infected or a lighter market, not more memory.
5. Repeat after the first month. Persistence will have grown with every base, so the end-of-cycle figure in week five is the one that matters for the long run.

In practice a server like this usually settles between 9 and 11 GB at the end of a cycle in its second month, which is why 12 GB is the comfortable plan and 10 GB the tight one. The numbers on your server will differ; the method will not.

Restarts are part of the design#

DayZ servers restart on a schedule, typically every three to four hours. It is not an admission of failure: server FPS degrades over a long session, memory climbs as the economy and players spread across the map, and the restart writes persistence cleanly and returns the server to its floor. The restart is also when loot and infected redistribute, and players have come to expect it.

The mission's db/messages.xml can announce restarts and shut the server down at a set uptime, and a panel schedule can run the restart and a backup on a cron expression. Restart schedules that help covers choosing the interval. On RE:NODE the Restart button is a clean stop, so persistence is written before the process ends; a server that hits its memory limit is stopped and restarted clean rather than left to swap. That is safe for the node and abrupt for players, which is one more reason to keep a margin under the limit rather than running at the edge.

DayZ plans on RE:NODE start at 6 GB with three port allocations, from $19 a month, up to 12 GB at the top of the ladder - the right shape for a 40-slot vanilla server at the bottom and a big Expansion server at the top. The install needs a Steam login that owns the game, entered on the Setup tab; a spare account is the sensible choice.

FAQ#

Is 6 GB enough for a DayZ server?

For a 30 to 40-slot vanilla server or a lightly modded one, yes. For a heavily modded server with Expansion's systems, traders and AI, plan on 10 to 12 GB. Turn on logMemory in serverDZ.cfg and read a full cycle before deciding.

Does DayZ use more RAM with more players?

Directly, not much. Each player costs some network and inventory state. Indirectly, more players build more bases, hoard more items and spread further across the map, and that is where the memory goes. Mods have a larger effect than slots.

Why does my DayZ server get slower before each restart?

Server FPS degrades over a long session as objects, bodies and player activity accumulate, and memory climbs with it. That is why DayZ servers restart every few hours. If it gets bad within an hour of a restart, look at loot multipliers, infected count and heavy mods.

Will doubling the loot use more memory?

Yes. The central economy keeps item counts near their nominal targets, so doubling nominals roughly doubles the number of loot objects on the map. It also adds work for the economy and for persistence. Raise the item types players want, not everything.

How much RAM does DayZ Expansion need?

Plan on 10 to 12 GB for a server running most of Expansion's modules with 30 to 50 players. The AI, market and vehicle modules add the most. Running only the modules you use, and keeping trader stock and AI counts sensible, keeps it towards the lower end.