We are rewriting an application which is write heavy (wont go into exact numbers but +00's of writes per second currently).<p>The original application was using a postgresql back-end (now severely struggling) but we are wanting to move to NoSQL due to changing schemas etc.<p>To give an idea of our setup.<p>We have two application server sets. One in the UK the other in the US, but only one database which is in the UK.<p>We want to have a setup where by as the company expands we can create more application server sets in different locations each with an application server and datastore.<p>Because write speed is more important than read we need a solution which will offer us the ability to add extra datastore nodes in order to increase write performance with the data being replicated across other locations.<p>I would like to know what people suggest as a nosql datastore which will offer us the ability to have master:x:master replication and a high write rate.