Should build machines launch local zen servers?

anonymous-edc · June 10, 2026, 3:32pm

Hi!

We recently enabled “zen for cooked output” in our project. And have a zen server hosted on our network. In addition to this, the project is also setup to launch a local zen server automatically when the editor boots.

My question is, how is the shared zen server populated with cooked data when everyone launches a local server?

Should build machines also launch local zen servers?

I could not find anything in the docs describing the interplay between several locally hosted servers + one shared server on the network. And so I’m looking for guidance on the optimal setup when using zen for build machines.

Patrick_Laflamme · June 10, 2026, 11:04pm

Hi,

They are two different things. The ‘Zen Server as Shared DDC’ and the ‘Zen Server as Cooked Outputs’. You are specifically asking for Zen Server as Cooked Output Store, but it might be useful to put both in perspective:

Zen Server as Shared DDC

Documentation:
- https://dev.epicgames.com/documentation/unreal\-engine/using\-derived\-data\-cache\-in\-unreal\-engine
- https://dev.epicgames.com/documentation/unreal\-engine/set\-up\-zen\-storage\-server\-as\-shared\-ddc\-for\-unreal\-engine
Local/Shared/Cloud DDC are typically populated on cache miss. The asset DDC is missing, it gets generated locally and the data is propagated to all caches configured writable.
- The DDC can be populated with the commandlet using the command UnrealEditor.exe ProjectName -run=DerivedDataCache -fill
On our build farm some agents use local Zen Server DDC caches, some don’t. The one that runs frequently for the same platforms has a local DDC, the agent running all kinds of jobs don’t. This is to balance the pressure on the Zen Shared DDC.

Zen Server as Cooked Output Store

The cooked data is written to the configured Zen server, the Zen server can be running locally or remotely. So you can share the same server between clients, but the remote setup is not widely used according to the system expert.
The cooked data is not propagated through the server hierarchy like DDC data is, instead, you use Snapshots to propagate cooked data between machines.
- See https://dev.epicgames.com/documentation/unreal\-engine/cooked\-data\-snapshots\-with\-zen\-storage\-server\-for\-unreal\-engine
The system expert recommended to keep the cooked output in the LOCAL zenserver that is automatically launched by the UnrealEngine cooker. If you want to move the cooked data around, the option that is best is using cook snapshots.

Regards,

Patrick

anonymous-edc · June 11, 2026, 10:36am

Hi Patrick!

Thank you for the detailed answer. I understand the setup better now & I sounds like we can stick with the configuration we have currently.

IE keep letting our build machines launch local zen servers, in addition to the shared one we already have deployed. The shared one would mainly be for “Zen Server as Shared DDC” then. And it should be filled up by our local instances as we go.

And for cooked data, it would only be stored on all the local zen servers. Unless we start using snapshots to move things around.

Best,

Anton