When I disconnect, coda loses all objects in a volume.
Check if the volume is a non-replicated volume. Non-replicated volumes have no version vector information, and can not be cached since conflicts are undetectable.
The solution is to create a replicated volume for a group consisting of only one server, a singly replicated volume. The objects in a singly replicated volume can stay in the cache while venus is running disconnected. (As long as there is enough cache-space).