multiple primaries & sync behaviour

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multiple primaries & sync behaviour

peschar

Hi,

I've got a setup with 2 primary nodes and several clients. If both nodes are online all data is synced properly.

When one of the primary nodes goes down any following database update by a client sets:
"sync_up_state": "synchronizing"
The clients do change their connection to the other primary node.

Once the offline primary node goes online again, the sync is finished, and an update is done on all secondary nodes.

What I like to know: is this the expected behaviour? I assumed that the other primary node and clients would continue 'normally'. e.g. syncing all updates to all clients. And when the primary node goes online again it will receive al missed updates.

Bernardo

Hello,

For consensus to take place, we need the majority of primary nodes on-line.

In your scenario the total number of primary nodes is 2, so the majority is also 2. This means that replication will only take place when both primary nodes are on-line.

If you add another primary node, then 1 of them can be off-line and the replication will take place, because the majority of 3 is 2.

peschar

Thanks for the clear reply!