Read/write transactions are automatically retried by the client library if the transaction is aborted by the backend. These retries use the backoff settings that are returned by the backend, or if no backoff settings are returned, the default backoff settings of the Rollback RPC. These default settings can however also cause transactions that are retried multiple times to fail with an Aborted error, if the total time that the retries are executed exceed the default total timeout of the Rollback RPC (30 seconds).