[Geoserver-users] GWC on cascading-WMS store

I have a cascading WMS store with a large amount of cached tiles. The source WMS is no longer accessible and when I use the gwc/service/wms endpoint access an area that's not cached, I get a ton of errors in my geoserver console (see below) and it slows down tile retrieval even if I return to an area with cached data.

Is there some way I can make my layer always return the existing cached data but avoid going back to the source cascading WMS store if it doesn't have a tile? In other words, can I get the failed/blank tiles immediately returned if they're not already available/cached locally?

Any advice is appreciated! I am on GeoServer 2.2.5.

Thanks!
Ashley

17 Nov 21:20:23 ERROR [geoserver.ows] -
org.geoserver.platform.ServiceException: Internal error
         at org.geoserver.wms.GetMap.run(GetMap.java:121)
         at org.geoserver.wms.DefaultWebMapService.getMap(DefaultWebMapService.ja
va:353)
         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)