What is the default erasure coding overhead in a three site VDC Federation with Replicate to All Sites enabled?

Question

Options

• A2x
• B3x
• C2.67x
• D3.99x

• A
  5% (1)
• D
  95% (21)

Explanation

In a three-site VDC Federation with Replicate to All Sites enabled, the total storage overhead compounds two factors: the default erasure coding overhead (approximately 1.33x from a standard 12+4 scheme, meaning 16 total chunks for every 12 data chunks) multiplied by the number of sites (3), yielding 1.33 × 3 ≈ 3.99x - making D correct.

Why the distractors are wrong:

• A (2x) reflects a simple 2-way mirroring scenario and ignores both the erasure coding overhead and the three-site replication factor.
• B (3x) accounts for three-site replication but assumes no erasure coding overhead - as if data were stored raw and perfectly distributed, which isn't the case.
• C (2.67x) is close to what you'd get with only two of the three sites contributing (1.33 × 2), suggesting it traps candidates who miscalculate the site count.

Memory tip: Think of it as a two-step multiplication - EC overhead first, then scale by sites: (12+4)/12 × 3 sites = 1.33 × 3 ≈ 3.99x. If you remember that "Replicate to All Sites" means every site holds a full EC-coded copy, the answer follows naturally.

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