  Grid Computing is a type of parallel and distributed systems that is designed
to provide reliable access to data and computational resources in wide area
networks. These resources are distributed in different geographical locations,
however are organized to provide an integrated service. Effective data
management in today`s enterprise environment is an important issue. Also,
Performance is one of the challenges of using these environments. For improving
the performance of file access and easing the sharing amongst distributed
systems, replication techniques are used. Data replication is a common method
used in distributed environments, where essential data is stored in multiple
locations, so that a user can access the data from a site in his area. In this
paper, we present a survey on basic and new replication techniques that have
been proposed by other researchers. After that, we have a full comparative
study on these replication strategies. Also, at the end of the paper, we
summarize the results and points of these replication techniques.
