How does F5 react for Disable, Unavailable and Offline Virtual server?

Disabling Virtual server : The VIP will stop processing the new connection and will send RST packet but still the older connection will be served to stop that delete connections from connection table in F5 .

Offline VS :

Offline ill be as the object/monitor associated with VIP has marked it offline .will not receive any traffic .

Unavailable VS:

The VS(enabled) is not currently available but might be available in future .

Here is good reference : http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm_configuration_guide_10_1/ltm_virtual.html