John: > master-master replication has all kinds of inherent issues if you're > concerned with data and transactional integrity. We have evaluated the problems and think we have found adequate workarounds for them. The sites we deploy are e-commerce sites so: 1. There are a lot more reads than writes. 2. When we need to write to the database, it is saving info for an order. All orders are independent of each other so there is no conflict for those. 3. Product updates, fulfillments, etc. happen once daily at night when the traffic is almost nonexistant. The updates are sent to only one server so there is no conflict there. The only potential place a conflict may occur is in the qty available for a specific product. The inventory system updates the inventory regularly so even if the number is wrong, it gets refreshed shortly thereafter. We even built an application layer on top of master-master replication to handle cases where a transaction fails. We are using this system for several large clients and it is working well. Being able to have geographical redundancy at a reasonable cost (A true cluster would be very high cost) outweighs the limitations. Thanks, Neil -- Neil Aggarwal, (281)846-8957 MySQL pre-installed on a virtual private server for $25/mo Unmetered bandwidth = no overage charges, 7 day free trial