Galera and in-memory I've got a question about Galera cluster + MySQL/MariaDB and RAM.

Basically, our MySQL cluster needs to run in-memory.

But:


We have 3 TB of data;
We don't have 100,000$ for RAM :)
We need High Availability.


In this case, is Galera a good solution? Will it run with 3 nodes (each with 128GB RAM and SSD's)?
A Galera node's memory usage is very similar to a normal MySQL/MariaDB standalone server. If 128GB is enough for a standalone server to handle your workload, it will be ok for a Galera node too.

Of course you can also have server with different characteristics. In which case, you will also need a load balancer that will take into account the servers "weight". You can use MaxScale, for example.