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# Scaling Techniques

## "Scaling Up" vs. "Scaling Out"

1. **Scaling up**: improving capacity, e.g., increasing memory, upgrading CPUs, or replacing network modules.
2. **Scaling out**: expanding the distributed system by deploying more machines

## Scaling Out

In particular, "scaling out" includes 3 techniques:

1. **Hiding communication latencies**
   * **asynchronous** communication
   * **server** check form vs. **client** check form
2. **Partitioning and distribution**
   * E.g., **DNS**
   * tree of **domains** and **zones**
3. **Replication**
   * **Caching**
   * Leads to **consistency** problems
   * **OK** for Web users but **not OK** for electronic stock exchanges and auctions