More Adaptation Policy Examples

• Self-maintenance and availability

  • maintain two copies of all dirty data stored only in volatile memory
  • if a disk fails, restore original redundancy level for objects stored on that disk

• Performance tuning

  • if accesses to a read-mostly object take more than 10ms on average, replicate the object on another disk

• Both (like HP AutoRAID)

  • if an object is in the top 10% of frequently-accessed objects, and there is only one copy, create a new replica. if an object is in the bottom 90%, delete all replicas and stripe the object across N disks using RAID-5.

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