摘要 |
In a network system including a plurality of devices connected to a network, a master device supplies general devices with shared data to be shared by the devices in the system. On each update of the shared data, the master device generates backup data (the shared data before the backup) and successively transmits a backup instruction to all the devices managed thereby, starting from a device of the lowest priority in the system. Each of the devices successively receiving the backup instruction acquires the backup data from a device having an immediately higher priority than itself. By the above operation, reliable backup of the shared data (enabling restoration of the shared data to that of several times ago after the update is repeated several times) is realized without overloading any device in the system even when the storage capacity of each device for storing the backup data is relatively small.
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