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How are the blockSpace thresholds calculated for Element

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Applies to

  • NetApp Element software
  • NetApp HCI Storage nodes

Answer

blockSpace thresholds are calculated based on the following equations:

  • Total block capacity - (largest node capacity + 3 % of total block capacity) = Cluster error threshold
  • Cluster error threshold / Total block capacity = % at which the system generates the error message

Additional Information

Example for five SF9605 nodes:

  • Total block capacity of five SF9605 nodes (5 x 8,640GB) = 43,200 GB
  • Largest node capacity = 8,640GB
  • 3% of total block capacity (43,200GB x 0.03) = 1,296 GB
  • Applying these values to the formula, the following results are obtained:
    • Total block capacity - (largest node capacity + 3 % of total block capacity) = Cluster error threshold
    • Cluster error threshold / Total block capacity = % at which the system generates the error message 
      • 43,200 - (8,640 + 1,296) = 33,264
      • 33,264 / 43,200 = .77 (or 77 %)

Interpret the results of the above example as follows:

  • A BlockClusterFull error code will appear when the cluster is 77% (33,264 GB) full
  • The system default for generating a warning severity message is 3% below the calculated error severity
    • In this example, the system would generate a warning severity when the cluster is 74% full
  • To be notified with a warning severity message before the 74% threshold is reached:
    • Specify the threshold percentage with the desired value on Cluster > Settings > Cluster Full Settings 
  • Example:
    • To receive a warning message at 10% below the error severity (77%):
      • Enter 10 in the Raise a warning alert when _ % capacity remains before Helix could not recover field
      • A warning severity alert will then be generated when 67% of the cluster is full

 

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