A method includes monitoring a sequence of transactions in one or more volumes. The transactions are transferred to a primary storage (112) in a given order, and are replicated to a secondary storage (114). The volumes belong to a volume group (204) for which the transactions are guaranteed to be replicated while retaining the given order. Artificial write transactions (228) are periodically issued to a protection application field, which is predefined in a given volume (212) belonging to the volume group. Records indicative of the transactions, including the artificial transactions, are stored in a disaster-proof storage unit (144). Upon verifying that a given artificial transaction has been successfully replicated in the secondary storage, the records corresponding to the given artificial write transaction and the transactions that precede it in the sequence are deleted from the disaster-proof storage unit.