Final answer:
It is true that a remote file server should know which files have been open by clients to recover from a failure. This knowledge helps maintain data consistency and facilitates seamless recovery of the file server and client operations.
Step-by-step explanation:
To answer the question, it is true that to recover a remote file server from failure, the file server should know what files have been open by clients. When a file server crashes or undergoes a failure, understanding which files were in use at the time of the incident can help in the recovery process and in ensuring data consistency. The server needs to track the state of each client's interaction with the file system to facilitate a seamless recovery and to determine if any data has been corrupted or lost. This information enables the server to pick up from where it left off, by knowing which files need to be restored or which client operations should be resumed