whenever an entry is read that can expire via max idle, we send a touch command to all owners so they all have the same relative access time. the get won't return until the touch command has completed.
scattered the backup can be any node and we don't know which nodes are backups. in this case the touch command goes to all nodes.
if you have max idle and eviction, any access of an entry on any node will update the eviction recency on all owners as well