SAP SE
Consistent backup of a distributed database system

Abstract:

In an executing database instance including a plurality of database nodes, creation of a backup of the executing database instance includes creation of a current savepoint in one of the plurality of database nodes by storing first modified pages of a cache of the database node in a datastore of the database node, transmitting a confirmation after storing the first modified pages, repeatedly identifying second modified pages of the cache and storing the identified second modified pages in the datastore, receiving an instruction to enter a critical phase and stopping the repeated identifying and storing in response to the instruction, blocking updates to the database node and transmitting a second confirmation, and receiving a second instruction and, in response to receiving the second instruction, identifying third modified pages of the cache and storing the third modified pages of the cache in the datastore. Pages associated with the current savepoint are identified and stored in the datastore, and the pages associated with the current savepoint are stored in a persistent media.