Crowd Data Center FAQ

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is page covers some of the most frequently asked questions about Data Center. If you have questions that aren't answered by this page, contact your Atlassian Enterprise Advocate, Atlassian's Enterprise team, or your Atlassian Expert.


How is Crowd Data Center different from Crowd Server?

 Crowd Data Center provides all the functionality of Crowd Server, plus the following features:

  • clustering the ability to run our Crowd instance on a cluster of multiple nodes, providing high availability and failover capability,
  • instant scalability: the ability to add or remove nodes from a running Crowd Data Center cluster with no extra downtime.
What is the migration path from Crowd Server to Data Center?

See Crowd documentation for detailed description of the migration process.

What kind of support is included with Crowd Data Center?

Support for Crowd Data Center is similar to the existing support for Crowd Server.

As enterprise customers you may also consider more advances support plans such as Premier Support and Technical Account Management. For more information about these services, contact your Atlassian Enterprise Advocate,, or your Atlassian Expert.

Can I use Crowd Data Center with Atlassian Server products?
Yes, Crowd Data Center supports the same functionality, and works with both Server and Data Center versions of all supported Atlassian products.
Please make sure that the Crowd ULR in Atlassian products you work with is pointing to the load balancer, rather than any specific node, to make sure they benefit from the Crowd Data Center's high availability.


Can I use a Data Center license on a single-node instance?

Yes, you can apply a Data Center license to a single-node instance of Crowd. When installing Crowd, simply skip the steps for adding more nodes.

What happens if we stop paying for the Data Center subscription service?


When your Data Center license expires, you will not be able to access or use the application until you provide a new valid license. 
Can I continue to use developer licenses in my test environment?

Yes, you can use a developer license for a staging environment.

Do I need to buy a license to evaluate Crowd Data Center?

No, you can get a free evaluation license from


How many cluster nodes I should use?

In order for hot failover to be possible, we recommend that you have a minimum of two cluster nodes. Adding more nodes will increase availability in case of node failures, and might increase throughput of some operations (notably authentication requests, if Crowd is handling authentication for your applications).

How does failover work in Crowd Data Center?

Because Crowd Data Center provides full active-active clustering, if a node goes down a failover can happen in seconds. You do not have to wait for a "cold standby" to start up, for all the data to replicate consistently, or for traffic redirection to propagate in the DNS. All this is handled automatically and seamlessly by Crowd Data Center and your load balancer, without intervention by the system administrator.

If a cluster node goes down, what happens to users who are logged in to that node?

In Crowd Data Center, user sessions are stored in the database so all operations related to user sessions can be handled by any node in the cluster. In case a node fails, the load-balancer will route traffic to other nodes preventing users from noticing any functionality loss. The same applies for sessions in the Crowd web interface (if you were in the process of doing a multi-step operation, like configuring a new application, you might need to restart that process).

Are there any specific load balancers that Atlassian recommends or has tested with?

You can choose any load balancer you like provided it support the following:

  • cookie-based session affinity ("sticky sessions")
  • determining node availability based on a healthcheck URL
  • SSL termination to offload HTTPS encryption and decryption

If you have no specific preference for your load balancer, you can find instructions for Apache and HAProxy on the Crowd Data Center load balancer configuration examples page.


Can Crowd Data Center be upgraded without downtime?

No. Crowd Data Center does not allow cluster nodes with mixed versions in the same cluster. Even if you upgrade nodes one at a time, there must always be a period of downtime between the old and new versions.

However, when properly managed, upgrades of a Crowd Data Center instance should take no more downtime than with an equivalent Crowd Server instance, and can often be considerably less. In Crowd Data Center, nodes can be taken offline one by one to perform the upgrade, leaving only the shutdown time of the last node on the old version and the startup time of the first node on the new version inside the downtime window. In Crowd Server instances this is only possible if you have provisioned an identical backup server for the purpose.

Are add-ons supported in Crowd Data Center?

Add-ons for Crowd Data Center can use the same APIs and services, however, some add-ons might need extra work, to run in a clustered environment. It's best to reach out to the add-on developer, to verify whether the add-on is compatible with Crowd Data Center.

For more information, see Developing Data Center compatible add-ons for Crowd.

Is CrowdID supported in Crowd Data Center?

No, currently CrowdID does not support clustering, and should not be running at multiple nodes at the same time. See this knowledge base article for details.

Last modified on Aug 9, 2017

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