Q&A about how Swarm licensing works

Q: How is Swarm licensed?

A: Swarm is licensed by physically used storage after protection.   It does NOT include trapped space or unused space, but it does include ALL live data (ie all versions).  
    Example 1:  if you have 20TB of data using 2x replicas, that is consuming 40TB of physical space, so 40TB of the license
    Example 2: If you have 20TB of data using EC4:2 that is using 30TB of physical space, so 30TB of license.

Q: Do you license in Usable or in RAW capacity

A: The licensing engine uses RAW capacity, however we often sell the license as Usable Storage, and at the time of license creation we estimate the raw capacity requirement based upon the usage requirement and the average protection schema. We can monitor whether this calculation is accurate or is being violated through our PhoneHome reports and other logs submitted in a support ticket.

Q: Can you have a license that is smaller or larger than the total storage available in the cluster?

A: Yes. In fact it is good practice to have slightly more physical space available than licensed space to cover for trapped space and other overhead

Q: What happen if I write more data than the license allows?

A: You will be unable to write any new data, including modifying existing data or metadata. 
    You will however be able to continue reading existing data.
    Note.  You may be unable to login to the cluster via the StorageUI, as the StorageUI requires an access token to be written to the cluster.

Q: Does a license update require a reboot?

A: No.  The license file itself is stored on the CSN/ SCS/ HTTP server, or potentially locally on the USB stick if the Storage node is booted from that USB. When you update a license, that process does not reach out to the storage node to change the license. The storage nodes themselves reach out to license.url to check the license every 15 minutes (configurable, but license.checkInterval is 900 seconds by default) and will apply those changes automatically.

Q: What happens if the Swarm Term license is expired?

A: When the license expires, new client writes are disallowed but the cluster allows reads.

Q: What happens if the License URL is not reachable?

A: If a node has fetched a valid license, it will keep using it.  If the node is rebooted and license.url is not available, it will not be able to apply the license even if the other nodes show a valid license.