In late 2009, Amazon introduced spot instances to offer their unused
resources at lower cost with reduced reliability. Amazon's spot instances allow
customers to bid on unused Amazon EC2 capacity and run those instances for as
long as their bid exceeds the current spot price. The spot price changes
periodically based on supply and demand, and customers whose bids exceed it
gain access to the available spot instances. Customers may expect their
services at lower cost with spot instances compared to on-demand or reserved.
However the reliability is compromised since the instances(IaaS) providing the
service(SaaS) may become unavailable at any time without any notice to the
customer. Checkpointing and migration schemes are of great use to cope with
such situation. In this paper we study various checkpointing schemes that can
be used with spot instances. Also we device some algorithms for checkpointing
scheme on top of application-centric resource provisioning framework that
increase the reliability while reducing the cost significantly