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### Cluster environment

In the Cluster environment, each file event listener has a "Node IDs" attribute which may be used for specification which cluster node will perform the checks on its local file system. There are following possibilities:

- No failover: Just one node ID specified - Only specified node observes the local/remote filesystem, however node status must be "ready". When the node isn't ready, file system isn't checked at all.

  To create a file event listener with no failover, select One of selected nodes in Initialize by and select one node from the table below.

- Failover with node concurrency: No node ID specified (empty input) - All cluster nodes with status "ready" concurrently check local/remote filesystem according to file event listener attributes settings. In this mode, when the listener is configured to observe local filesystem, each cluster node observes its own local file system. So it's useful only when the observed path is properly shared among the cluster nodes. It may behave unpredictably otherwise. On the other hand, when the listener is configured to observe remote filesystem, listeners running on different cluster nodes may connect to the same remote resource. The nodes use locking mechanism when accessing the local or remote filesystem, so the listeners running concurrently on different nodes can't get to the conflict.

  To create file event listener with node cuncurrency, select Any node in Initialize by.

- Failover with node reservation: More node IDs specified (separated by comma) - Just one of specified nodes checks its filesystem. If the node fails from any reason (or its status isn't "ready"), any other "ready" node from the list continues with checking. Please note, that when file event listener is re-initialized on another cluster node, it compares last directory content detected by the failed node with the current directory content.

  To create a file event listener with node reservation, select One of selected nodes in Initialize by and select more nodes.

In standalone environment, the "Node IDs" attribute is ignored.

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