By maintaining multiple copies, it becomes possible to provide better protection against corrupted data. a. true b. false An invalidation protocol propagates a update to other copies, informing them their data are no longer valid. a. true b. false In active replication, each replica has an associated process that carries out update operations. In contract to other protocols, updates generally are sent to each replica. a. true b. false A consistency model is essentially a contract between processes and the data store. It says that if processes agree to obey certain rules, the store promises to work correctly. a. true b. false The remote-write protocol allows processes to perform read operations on a locally available copy, but forward write operations to a (fixed) primary copy. a. true b. false