All replication failures are picked up by the scanner which runs at a one minute frequency, each time scanning upto a sixteenth of the namespace. Object versions marked `PENDING` or `FAILED` are re-queued for replication.

- MinIO also supports expansion of existing clusters in server pools. Each pool is a self contained entity with same SLA's (read/write quorum) for each object as original cluster. By using the existing namespace for lookup validation MinIO ensures conflicting objects are not created. When no such object exists then MinIO simply uses the least used pool to place new objects.

### There are no limits on how many server pools can be combined

## Implementation

ILM tiering takes place when a object placed in the bucket meets lifecycle transition rules and becomes eligible for tiering. MinIO scanner (which runs at one minute intervals, each time scanning one sixteenth of the namespace), picks up the object for tiering. The data is moved to the remote tier in entirety, leaving only the object metadata on MinIO.