"... After the cache is created, if you don't want to continue storing all of the source data on your server, you can remove some of the layers from the source map document. Leave at least one layer in the map document (a suggestion is a simple feature class with one feature covering the map extent), and leave the map document in the coordinate system used to create the cache. After you restart the service, you can safely remove the source data off the server for any layers you removed. As long as the service name and the cache name stay the same, users will continue to see the cache when they view the service.
Keep in mind that if you use this technique, users will not get any meaningful results when they query the service. If you want to maintain some queryable layers, you should leave them in the map document and leave the source data for those layers on the server. ..."
if you call service in mode dynamic service you see only layers in your msd/mxd