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[2] Counter based re-balance
In the second case, which is relevant only for the enabled persistence mode, re-balance is used to restore the consistency of the data if the node (s) was absent for some time in the topology under the load.
When the node re-joins the topology, the partition update counter will be analyzed to determine how much the partition has “lagged” from other copies.
Depending on how much the partition is lagging behind, the second type of rebalance can use the write-ahead log as a data source. In this case, the re-balance can be performed without a complete reloading of the partition and is called “historical”.
Another scenario for the occurrence of [2] is the activation of the grid, which was turned off accidentally (under load)where some nodes may have stale data.
Re-balance is the exchange of supply and demand messages between nodes. A message demand sends a node on which the partition is not consistent. Supply messages contain the next update batch and are sent demand message is sent from node where partition has stale data to node with actual data. Supply messages is send in response to demand messagesmessage.