How do I propagate failures from upstream wms-servers?

[Ben Tuttle]

>
> I think the silence is an indication that there is no way to ask
> MapServer to produce an exception in this case at the moment.
>
> I'd suggest you file a ticket proposing that as an enhancement.
>
> Daniel
> --
> Daniel Morissette
> http://www.mapgears.com/
>

Given that mapserver can't do this at the moment have you considered
other options? While it probably not as efficient you might be able to
set up a cron to watch your cache for new images and do a "gdalinfo
-mm" on each new tile in the cache and delete tiles with only one
value (ie blank tiles).