Db2 purescale and Oracle RAC

IBM announced a new technology called Purescale recently.It is basically a technology that excels in horizontal scalability.

So what is horizontal scalability??How is it different from vertical scalability??

Horizontal scalability is the ability to add capacity by adding nodes to the cluster whereas vertical stability is the ability to increase capacity by adding extra resources to the existing entity/server.

Purescale is aimed at achieving 3 important goals:
1)Application transparency: No coding changes are required when you add extra nodes

2)Unlimited capacity:This is achieved by adding as many nodes as needed.But there are limitations on the platforms to begin with

3)Data availability:This system aims at zero downtime and is completely available if one or many nodes fail

Is Purescale a replacement for HADR??

No. Purescale is not a replacement and it has only one shared database copy.So, if HADR can be applied for a purescale system it is the optimal availability scenario.IBM thinks that they can do this in the coming days


Oracle RAC Vs DB2 Purescale:Which is better??

When you use Oracle RAC lot of application changes have to be made when we add new nodes.But with Purescale the application is completely transparent to the changes in nodes.Also Purescale has centralized resource management system that manages the lock and other resources.