I have to move our database to a larger disk. The indexes are on a separate disk. On our test machine, searchs seem to be fine without reindexing but would like to confirm that.
If you specified an indexspace when creating the indexes then when you copy the database it will still point to the same place for the indexes, and will work fine. Since you will then have two databases pointing to the same indexes you should make sure that you only use one of them, especially once updates start.
If you did not specify an indexspace then the indexes will be created in the database directory, and should be moved to the new database directory, and that will also work fine. Since you have copied the indexes in this scenario there is not the same risk of two databases updating the same indexes.