Skip to main content
Hitachi Vantara Knowledge

Considerations for modifying an erasure coding topology

These considerations apply to modifying an erasure coding topology:

  • You can modify these properties of an active erasure coding topology:
    • Name
    • Description
    • Distribution method
    • Minimum object size for erasure coding
    • Erasure coding delay
    • Restore period
  • You cannot modify a retiring or retired erasure coding topology.
  • Changes you make to the configuration of an erasure coding topology apply to existing objects as well as to new objects.
  • When you change the distribution method from chunk distribution to full-copy distribution, previously distributed chunks are restored to full copies of object data if the erasure coding delay has not yet expired. The full copies are reduced to chunks again after the erasure coding delay expires.
  • When you change the distribution method from full-copy distribution to chunk distribution, previously distributed full copies of object data are reduced to chunks after the erasure coding delay expires.
  • When you reduce the minimum object size for erasure coding, for any given object that was previously subject to whole-object protection but is now subject to erasure coding:
    • On a system where the object is not metadata-only, the object data is reduced to a chunk after the erasure coding delay expires
    • On a system where the object is metadata-only:
      • If the erasure coding topology is configured for chunk distribution, the system receives a chunk for the object.
      • If the erasure coding topology is configured for full-copy distribution, the system receives a chunk for the object if the erasure coding delay has already expired. If the erasure coding delay has not yet expired, the system receives a chunk for the object when the delay expires.
  • When you increase the minimum object size for erasure coding, for any given object that was previously subject to erasure coding but is now subject to whole-object protection:
    • On a system where the object is not supposed to be metadata-only:
      • If the system has a chunk for the object, the chunk is restored to a full copy of the object data
      • If the system has a full copy of the object, the full copy remains as is
    • On a system where the object should be metadata-only, the chunk for the object or the full copy of the object data, as applicable, is deleted
  • When you increase the erasure coding delay for an erasure coding topology configured for full-copy distribution, chunks for existing objects for which the new delay has not yet expired are restored to full copies of the object data.
  • When you decrease the restore period, objects that are currently in a restored state and for which the new restore period has already expired are returned to their previous erasure-coded states.
  • When you increase the restore period, objects that are currently in a restored state and for which the new restore period has not yet expired are returned to their previous erasure-coded states after the new restore period expires.
  • You can modify an erasure coding topology from any system in the topology.
  • While a system in an erasure coding topology is being upgraded, you cannot use that system to modify the topology.

 

  • Was this article helpful?