An ARK cluster is two or more dedicated servers started with the same -clusterid= and pointed at the same directory with -ClusterDirOverride=. When a player uploads a character, a creature or an item at an obelisk or transmitter, the server writes it to a file in that directory; when they arrive on another map in the cluster, that server reads it back. That is the entire mechanism. There is no central service and no network link between the servers - just a folder both of them can write to. Everything that goes wrong with clusters goes wrong because that folder is not shared, is not backed up, or is read by a server whose rules say no.
This post assumes each map already runs on its own. The ARK: Survival Ascended setup guide covers a single server; here we connect several.
What a cluster is, and what it costs#
Each map in a cluster is a separate, complete server: its own process, its own install, its own save, its own ports, its own memory. A cluster of three maps is three servers that happen to agree on a directory. Nothing is shared except transfer data.
That has two consequences people underestimate.
- Cost scales with maps, not players. Ten players spread across three maps use roughly three times the memory of ten players on one map, because each map holds its own world, its own wild creatures and its own structures regardless of who is on it. A quiet map with nobody on it still costs most of what a busy one does.
- Population spreads thin. A server with twelve active players feels alive. The same twelve over three maps feel like three servers with four people each. Clusters suit communities that are big enough to fill more than one map, or groups who want to work through the story maps in sequence while keeping their creatures.
| Cluster size | Memory, all maps together | Suits |
|---|---|---|
| One map, no cluster | 10-16 GB | Groups under about fifteen |
| Two maps | 20-32 GB | A main map and a progression or event map |
| Three to four maps | 30-64 GB | Communities with 30+ regulars |
| Five or more | 50 GB upwards | Large public communities with staff |
These figures follow the single-server sizing in how much RAM an ARK server needs; a cluster does not change the per-map number, it multiplies it. CPU works the same way - each map wants a fast core of its own for its game thread.
The launch arguments that make a cluster#
Three launch arguments are involved, and two of them must be identical on every server.
TheIsland_WP?listen?SessionName=Longship Island?Port=7777?QueryPort=27015?RCONPort=27020 -clusterid=longship-c1 -ClusterDirOverride=/srv/ark/cluster -NoTransferFromFiltering -logScorchedEarth_WP?listen?SessionName=Longship Scorched?Port=7779?QueryPort=27017?RCONPort=27022 -clusterid=longship-c1 -ClusterDirOverride=/srv/ark/cluster -NoTransferFromFiltering -log| Argument | Must match across servers | What it does |
|---|---|---|
-clusterid= | Yes | Names the cluster. Servers only see transfer data with the same ID |
-ClusterDirOverride= | Yes, same physical folder | Where transfer data is written and read |
-NoTransferFromFiltering | Should | Relaxes the check on where uploaded data came from |
The cluster ID is a free-form string. Make it unique and a little obscure - a cluster ID that another community also uses is harmless only as long as you never share storage with them, and on a host where the cluster directory sits in a common location, it is a collision waiting to happen. longship-c1 is better than cluster.
-ClusterDirOverride names a parent folder; the server keeps its transfer files in a subfolder named after the cluster ID. If you leave it out, each server uses a default location inside its own install, which means each server has its own private "cluster" folder and nothing transfers. This is the single most common reason a newly built cluster appears to work - the obelisk lets you upload - and then nothing shows up on the other map.
Every server also needs its own game port, query port and RCON port, and its own SessionName. Two servers on one address with the same port will not both start. Keep a short table of which map has which ports; you will need it when someone asks why they cannot find Scorched Earth in the browser. Game server ports explained covers why the query port is the one that decides whether a server is listed.
Upload and download rules#
Whether something can leave a map and whether it can arrive are separate switches, set per server in GameUserSettings.ini under [ServerSettings].
| Key | Effect when True |
|---|---|
NoTributeDownloads | Nothing can be downloaded on this server at all |
PreventDownloadSurvivors | Characters cannot arrive here |
PreventDownloadItems | Items cannot be downloaded here |
PreventDownloadDinos | Creatures cannot be downloaded here |
PreventUploadSurvivors | Characters cannot leave from here |
PreventUploadItems | Items cannot be uploaded here |
PreventUploadDinos | Creatures cannot be uploaded here |
For an open cluster, set all seven to False on every server. Restrictions are what make a cluster interesting, though, and the per-server design lets you build one-way rules:
- A progression cluster where creatures can go forward to later maps but not come back to earlier ones: allow dino uploads on the early maps and dino downloads on the later ones, but block downloads on the early maps.
- An event or arena map where people bring characters but not creatures:
PreventDownloadDinos=Trueon the event server only. - A "fresh start" map that accepts survivors but nothing they carry: block item and dino downloads there.
Write your rules down before you set them, and post them where players can read them. A creature that cannot come back from a map is a creature somebody will lose, and the server should not be the first to tell them.
[ServerSettings]NoTributeDownloads=FalsePreventDownloadSurvivors=FalsePreventDownloadItems=FalsePreventDownloadDinos=TruePreventUploadSurvivors=FalsePreventUploadItems=FalsePreventUploadDinos=TrueTransfer limits and expiry#
Uploaded data does not wait forever, and it is limited in quantity. The keys below control that. Defaults have varied between releases, so check what your build does before you rely on a number.
| Key | What it controls |
|---|---|
MaxTributeDinos | How many creatures one player can hold uploaded at once |
MaxTributeItems | How many item stacks one player can hold uploaded at once |
TributeDinoExpirationSeconds | How long an uploaded creature survives before it is deleted |
TributeItemExpirationSeconds | How long an uploaded item survives |
TributeCharacterExpirationSeconds | How long an uploaded character survives; 0 usually means never |
The expiry timers are the ones that hurt. A player uploads their best creature on Friday, forgets about it, and comes back the following week to find it gone - not lost to a bug, but expired on schedule. On official-style settings, uploaded creatures and items expire after about a day. On a private cluster where people play a few evenings a week, raising the creature and item timers to a week or longer avoids this whole category of support request. Do not set them to zero unless you have confirmed what zero means on your build; for some keys it means "never expire" and for others it is not honoured.
The quantity limits exist to stop the cluster folder from becoming a warehouse. Uploaded data is stored outside both worlds, which makes it a tempting place to keep things safe from raids, and on a PvP cluster that is exactly what people will use it for. Keep the limits modest on PvP and relax them on PvE.
Map-specific creatures and items#
Not every creature is allowed to leave its home map. Some creatures and items are restricted to the maps they come from, either by the game or by the transfer rules of the map they would arrive on. The usual examples are the story-map creatures that the game treats as part of that map's progression. A server setting, CrossARKAllowForeignDinoDownloads, relaxes the restriction for creatures arriving from other maps on builds that honour it; behaviour here has changed between Evolved and Ascended and between patches, so test with one creature you can afford to lose before telling players a transfer is safe.
Element and some boss-related items have also been restricted in transfers at various points. The rule of thumb is the same: if a transfer would let someone skip a map's progression, assume the game might block it and test.
Mods and clusters#
Mods are where clusters get fragile. A creature or item from a mod is a reference to something the mod defines. If the destination map does not run the same mod, the reference points at nothing:
- An item from a mod that the destination server does not load is deleted on download, or never appears.
- A creature from a missing mod does not arrive.
- A character wearing modded armour may arrive without it.
The safe rule is to run the same mod list, in the same order, on every server in the cluster. Where that is not possible - a map mod that only one server needs, for example - Ascended supports listing mods as passive on the other servers with -passivemods=, which loads a mod's data without its content so that its items survive a transfer. Behaviour of passive mods has shifted with updates; verify with a test transfer after every mod change. ARK mods from CurseForge on a server covers the mod list itself.
Update mods across the cluster at the same time. A cluster where one map runs version 1.4 of a mod and another runs 1.5 can transfer data that the older version cannot read. Stop all the maps, update, and start them together.
Where the shared directory has to live#
This is the honest constraint of clusters, and the one that decides where you can run one.
The directory has to be one physical folder that every server writes to. On a single machine that is trivial: point every server at the same path. Across machines it means a network filesystem, which works but adds latency and a new way to fail - a network share that drops mid-write can corrupt a transfer file, and the server will not tell you it happened.
On panel-based hosts, including Pterodactyl and anything built on it, every server is its own container with its own files. Two servers on the same account do not see each other's folders, and a shared cluster directory between them is something the host has to set up deliberately, if they do it at all. Ask before you buy the second server, and if the answer is vague, assume no. A single machine you control - a dedicated server or VDS - is the straightforward way to run a cluster, because all the maps can share one local path. Multiple game servers on one VDS covers splitting one machine between several servers, which is exactly what a cluster is.
Backups, restarts and cluster data#
The cluster directory is not part of any map's save. Back it up on its own, on the same schedule as the maps. If you restore the maps but not the cluster folder, every item and creature that was in transit at the time of the backup is gone, and if you restore the cluster folder without the maps, you can create duplicates: a creature that was uploaded after the map backup was taken exists both in the restored map and in the cluster folder.
The safe procedure for a full rollback is:
- Stop every server in the cluster.
- Restore every map save and the cluster directory from backups taken at the same time.
- Start the servers.
Restarts deserve the same coordination on a busier cluster. Restarting all maps at the same scheduled minute is simpler for players and avoids the edge case where someone uploads on map A, map B restarts, and they arrive on a server that is not there yet. A daily restart for ARK is normal anyway; restart schedules that help covers when and how to warn players.
Admin work across a cluster#
Admin commands are per server. Bans, kicks and broadcasts on one map do not propagate to the others; a player banned on The Island can still join Scorched Earth. Ban on every map, or use a tool that sends RCON commands to all of them. RCON safely covers keeping several RCON ports usable without exposing them, and each map should have its own ServerAdminPassword only if you have a reason - one password for the cluster is easier to rotate.
Keep the gameplay settings identical unless a map is meant to be different. Players move their breeding to whichever map has the fastest rates, and their farming to whichever has the best harvest. If you do want a difference, make it deliberate and announce it. The ARK settings guide has the keys.
Troubleshooting transfers#
Uploads work but nothing appears on the other map. The servers do not share a directory. Check that -ClusterDirOverride is set on both and that it resolves to the same physical folder, not two folders with the same name.
The other map is not in the transfer list. Check that the -clusterid values match exactly, including case, and that both servers are running.
A creature uploaded fine and could not be downloaded. A PreventDownloadDinos on the destination, a map-specific creature, or a missing mod.
Items vanished from the upload list after a few days. The expiry timers. Raise TributeItemExpirationSeconds and TributeDinoExpirationSeconds.
A survivor arrived without their gear. Items from a mod the destination does not run. Align the mod lists or use passive mods.
After a restore, players have duplicate creatures. The maps and the cluster folder were restored from different points in time. Restore both from the same backup set.
FAQ#
Do all maps in an ARK cluster need to be on the same machine?
No, but they all need to read and write the same cluster folder. On one machine that is a shared path. Across machines it needs a network filesystem, which is slower and adds failure modes.
Can I run a cluster with different mods on each map?
You can, but modded items and creatures will not survive transfers to maps without the mod. Run the same list everywhere, or list the missing mods as passive on the maps that do not need their content.
How do I stop players bringing tames to a new map?
Set PreventDownloadDinos=True in that server's GameUserSettings.ini. Characters and items can still arrive unless you block those as well.
Why did my uploaded dino disappear?
Most likely it expired. Uploaded creatures are deleted after TributeDinoExpirationSeconds, which on default-style settings is about a day. Raise it on a private cluster.
Is a cluster worth it for six players?
Rarely. You pay for every map whether anyone is on it or not, and six people across two maps feels empty. Play one map, then wipe and move to the next when the group is ready.
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