Two-phase commit

In computer science, especially in durability studies, a two phase commit allows data to be written to more than one location and for all operations to be rolled back, if one or more of the operations fails.

In essence:

• Phase 1

Each participant's resource manager coordinates local operations

If successful

respond "OK"

If unsuccessful

either allow a time-out or respond "NOT OK"

• Phase 2

If all participants respond "OK":

Coordinator instructs participating resource managers to "COMMIT"

Participants complete operation

Otherwise:

Coordinator instructs participating resource managers to "ROLLBACK"

Participants complete their respective local undos