When you are configuring services of Access Gateway, the OK button saves the change to browser cache except on the Configuration page. The Configuration page (Devices > Access Gateways > Edit) provides a summary of the changes you have made. The Cancel Change column allows you to cancel changes to individual services. When you click OK, the changes are saved to the configuration datastore, and you no longer have the option to cancel changes to individual services.
If you don’t save the changes to the configuration datastore and your session times out or you log out, any configuration changes that are saved to browser cache are flushed. These changes cannot be applied to other members of the cluster because they are no longer available. To prevent this from happening, save the changes to the configuration datastore.
It is especially important to save the changes to the configuration datastore when you select to update individual members one at a time rather than update all members of the cluster at the same time. Updating members one at a time has the following benefits:
When you update all servers at the same time, the site goes down until one server has finished updating its configuration. If you update the cluster members one at a time, only the member that is updating its configuration becomes unavailable.
If you update the servers one at time, you can verify that the changes are behaving as expected. After testing the configuration on one server, you can then apply the saved changes to the other servers in the cluster. If you decide that the configuration changes are not behaving as expected, you can revert to the previously applied configuration. See Reverting to a Previous Configuration.
Some configuration changes cannot be applied to individual cluster members. For a list of these changes, see Modifications Requiring an Update All.