Scale out the logic tier, scale up the storage tier
The logic tier is the business logic. In a three tier architecture, this comprises the Web applications. As such, Web apps regardless if they are deployed to physical machines or as virtual machines are expected to be decommissioned anytime. Thus, in the event of system maintenance or downtime, the continuity of online business is not disrupted.
Scaling out means deploying your apps to commodity hardware so you have three options:
- physicalization – deploy to physical machines
- hardware-level virtualization like KVM or Xen
- OS-level virtualization like Docker or SmartOS Zones
On the other hand, when I say scaling up, I am not referring to big fat machines like those being sold by the big boys. Instead, I am referring to commodity hardware that have larger memory and faster CPU compared to their little counterpart in the logic tier.
RDMBS and distributed storage system like Ceph need to be installed on dedicated bare-metal servers so these are mean and brawny machines.