The V System
The designers of the V System recognized the possibility of message loss due to message buffer overflow, and their solution was to make use of larger buffers and to modify the kernel to introduce a random delay when replying to a group send, thereby reducing the number of messages in a queue at any time. This imposes a consistent overhead on all group replies but still does not ensure that buffer overflow will never occur (if the number of different groups interacting with each other increases then even with this delay it is still probable that the finite sized message queues will overflow).
When servers reply to a client they do so on a many-to--one basis i.e., all servers which received a request from a particular client will attempt to reply to that client (and not to any replica group the client may be a member of). This means that there is the possibility of members of the same group taking different actions as a result of local events such as timeouts (resulting in state divergence), because the servers replied to some, but not all, clients on time.