Hello @Evgeny Vasilyev, can’t think of any built in functionality to limit the ability to associate assets that may have some form of “Under Maintenance” identifier. I like this idea, you should add it as a feature request here. There are a couple really unrealistic approaches to solve this, for example a custom application that filters asset results might be able to accomplish something like this, but there isn’t a way to make that available to requesters, just agents. You could use custom objects that list all your “Available” assets in a service request field and then have workflow associate the asset based on the returned record of a reader node but that requires a lot of upkeep to make sure its up to date. My last idea, and maybe more realistic, would be to create an “Under Maintenance” asset type and change the type of assets as they go under maintenance to this type. Doing this, it may deter requesters from selecting devices that are defined as under maintenance.
Just some thoughts, take care!