What is net gain?

[erik777]

I am trying to create performance metrics, tests and capacity planning. We would like to use JBoss in our first release of an application.

Can someone help me understand the full performance equation when you cluster. Obviously, you are doing it to obtain a net gain, with failover. The question is, in computing this net, how much is lost because of feature loss, contention and other issues? Do you lose the benefit of EJB caching on updateable EJBs?

Does anyone have an estimate of the net gain if you cluster two servers with the exact same hardware versus using just one of them? Obviously, the gain is going to be less than 100%.

Thanks,

Erik

[slaboure]

The exact gain depends on your architecture (stateless, stateful, etc)

All usages are not for the same reason though: some people use it for failover whereas other use it for scalability.

Currently we don't provide distributed locking at the application server level. For this, use Gemstone Facet product (JBoss partner). So you will have to use commit option B/C and pessimistic locking at the DB level. Shortly, we will provide easy distributed caching for non strict data in commit option A (but no distributed-locking).

If you have some numbers, we are interested in.

Cheers,


Sacha