Mirroring

Data mirrored between grids is a logical copy of the user data available on the primary grid and is copied to the mirror grid only if a checkpoint has been taken at the primary grid (either a user-created checkpoint or a periodic checkpoint causes mirroring). Until all copysets in the primary grid have confirmed that their data has been mirrored, data in the checkpoint being mirrored is not available.

Bulk Mirroring

If a mirror grid has no previous checkpoints available or if the primary grid has insufficient information to identify the rows that changed since the last mirrored checkpoint, bulk mirroring is used. During bulk mirroring, all rows present in the checkpoint being mirrored are sent to the mirror grid.

Incremental Mirroring

ActiveSpaces attempts to minimize the data sent between grids whenever possible by using incremental mirroring. When a mirror grid has a previous checkpoint as the starting point, and the primary grid has sufficient information to identify all rows that changed, only rows that were updated or deleted are sent to the mirror grid.