Site Autonomy

Site autonomy refers to whether the operations of one site are affected seriously by those of another. There is complete site autonomy if one site's ability to do its work is independent of its connectivity to another site, and the state of operations at that site. For example, the use of 2PC makes every change to data dependent on whether every other participating site is able to accept the transaction successfully and immediately. If one site is unavailable, no work can proceed. At the other end of the spectrum, in merge replication, every site works independently and can be completely disconnected from all other sites. Merge replication has high site autonomy but not guaranteed consistency. 2PC has guaranteed tight consistency but a total absence of site autonomy. Other solutions are somewhere between both dimensions.