"Some, but not all applications can be repaired even while they are open and being used. The criteria for doing this are whether the application is running in the background, if it booted properly, and whether it can be put into sleep mode. There are many different tools available that allow you to monitor the performance of applications and systems to determine if a problem exists in what the root cause may be. Once you understand the problem and have determined what will be required to remediate it, you can decide whether you can do this while the application is still up and running or require a system shutdown. When a shutdown is required, the users should be notified in advance, and the application and any data should be backed up before shutting it down. If you can fix it while the application is still running, make sure that the data is mirrored, so if a problem occurs, it can be retrieved."