In one aspect, a method includes checking periodically, using a processor, for a value associated with data in a data block in a higher tier journal stored on a first storage array having deduplication-based functionality and copying the data in the data block from the higher tier journal to a lower tier journal in a second storage array if the data in the data block exists only in an UNDO stream in the higher tier journal. The first storage array and the second storage array are used in a continuous data protection system to replicate a volume. The method also includes replacing the data in the data block in the journal with a zero block if the data in the data block exists only in the UNDO stream.