Caching¶

• Information copied from slower to faster storage
• Faster storage is checked first to determine if information is there
  • if it is, uses cache
  • if not, copy data to cache and use there

Consistency and Coherency¶

Same data may appear in different levels. Changing the copy in register make it inconsistent with other copies.

• Single task : no problem
• Multi task : need to obtain the most recent value
• Distributed system: really difficult