Clustering
Clustering databases is hard
- Must partition or replicate data on disk
- Transactions are slow & complicated over ɭ machine
- Big sites may have one massive UNIX box + failover
Clustering application servers is medium
- Manage non-transactional data and in-memory sessions
Clustering Web servers is easy
- eBay has more than 200 NT Web servers
- Load balancers sit in front (e.g., F5 Networks)