Garbage collection of tombstones for optimistic replication systems

A computer-readable medium having computer-executable instructions, comprising:

• maintaining an époque timestamp on a first member of a replica set, the replica set including at least two members, at least some of the members being online at any given time;
• periodically updating the époque timestamp on the first member;
• propagating the époque timestamp from the first member to other members of the replica set that are online;
• initiating a synchronization between at least two of the members of the replica set;
• comparing époque timestamps;
• if the époque timestamps are skewed, stopping the synchronization.

A computer-readable medium having computer-executable instructions, comprising:

• synchronizing objects on a plurality of members of a replica set via one or more joins;
• deleting at least one of the objects from at least one of the members and marking the deleted object with a tombstone;
• deleting the tombstone;
• comparing a version vector of one of the members of the replica set with a version of the object that remains undeleted to delete the version that remains undeleted.

A system for synchronizing files, comprising:

• a plurality of members participating in a replica set, wherein each member is associated with a data store into which objects that are to be replicated are stored and a database that maintains information about the objects stored in the data store, wherein a first member participating in the replica set is configured to perform acts, comprising:
• creating an object;
• transmitting the object and information associated therewith to a second member of the replica set via a join operation;
• indicating that the object is deleted via a tombstone;
• and
• deleting the tombstone;
• and wherein members are arranged to communicate with each other to determine whether any member includes an object for which a tombstone has been deleted.

A computer-readable medium having computer-executable instructions, comprising:

• attempting to synchronize an object on a first and second member of a replica set via one or more joins, each member having a database associated with resources stored on the member;
• in an operation other than the one or more joins, comparing the databases on the first and second members;
• detecting, via at least the comparing of the databases, that the object was synchronized incorrectly;
• and
• correcting the object on the second member with data from the first member.