How reliable is master-slave replication?

Question

I was watching this screencast at RailsLab where the presenter claims that it's possible to have a master DB for write operations and a slave DB for read operations. While for certain types of Web sites (eg blogs, social networks, Web 2.0 sites, etc.) it is acceptable for the master and slave DBs not to be 100% synchronized for short periods of time, but AFAIK this is not acceptable in domains such as banking and insurance.

My question is that if such usages of master-slave replication are reliable enough for banking and insurance (and similar) applications where there's no room for violation of the integrity of the system. In other words, if it is acceptable for the master and slave DBs to be out of sync for short periods of time.

If not, what horizontal (not vertical) solutions are available for scaling a database systems in such environments that there's absolutely no room for system integrity to be compromised?

Answer 1

If not, what horizontal (not vertical) solutions are available for scaling a database systems in such environments that there's absolutely no room for system integrity to be compromised?

Clustering