Interactive applications such as email, calendar, and
maps are migratingfrom local desktop machines to data cen-
ters due to the many advantages offered by such a computing
environment. Furthermore, this trend is creating a marked
increase in the deployment of servers at data centers. To ride
the price/performance curves for CPU, memory and other
hardware, inexpensive commodity machines are the most cost
effective choices for a data center. However, due to low avail-
ability numbers of these machines, the probability of server
failures is relatively high. Server failures can in turn cause
service outages, degrade user experience and eventually re-
sult in lost revenue for businesses. We propose a TCP splice-
based Web server architecture that seamlessly tolerates both
Web proxy and backend server failures. The client TCP con-
nection and sessions are preserved, andfailover to alternate
servers in case of server failures is fast and client transpar-
ent. The architecture provides support for both determinis-
tic and non-deterministic server applications. A prototype of
this architecture has been implemented in Linux, and the pa-
per presents detailed performance results for a PHP-based
webmail application deployed over this architecture