ServiceNow Data Center

There are 10 support centers and 11 data center pairs for a total of 21 data centers. ServiceNow’s data centers are arranged in pairs. 
Their data center pairs span five continents:

Asia
Australia
Europe
North America
South America

All customer production data is stored in both data centers and kept in sync using real-time database replication. Both data centers are active at all times, each with the ability to support the combined production load of the pair. A production instance for one customer may be primary out of one data center in the pair while a production instance for another customer may be primary from the other.

ServiceNow maintains continuous, asynchronous replication from the database in the current primary data center (read-write) to the secondary data center (read-only). To transfer a customer instance from a primary to a secondary data center, ServiceNow designates the secondary to be the primary and the primary to be the secondary.

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Reference: https://docs.servicenow.com/