A data processing system includes at least a first storage system, a
second storage system and a third storage system. The third storage
system maintains a replication of data stored in the first storage
system. When updating data in the first storage system, the first storage
system updates the replication of data stored in the third storage system
and creates a journal. The journal is formed from a copy of data used for
update and update information such as a write command for update, etc.
The second storage system also maintains a replication of data stored in
the first storage system. The second storage system obtains the journal,
and updates data stored therein corresponding to data stored in the first
storage system in the order of data update performed in the first storage
system. When updating data stored in the third storage system
corresponding to data stored in the first storage system, the third
storage system creates a journal using data update numbers created in the
first storage system. When the first storage system fails, the second
storage system obtains the journal from the third storage system, and
updates data stored therein corresponding to data stored in the first
storage system in the order of data update performed in the first storage
system.