A customer requires efficient capacity and protection for large, immutable video archives across three sites. Which ILM layout is ideal?

• A. EC 4+2
• B. 3-copy replicated
• C. EC 2+1
• D. Balanced consistency

Answer: (A)

For large immutable video archives spread across multiple sites, the best approach combines protection with efficient use of storage through erasure coding rather than simple replication. Erasure coding splits data into chunks and adds parity, so you can lose several chunks and still reconstruct the original data, delivering strong protection without the heavy overhead of duplicating every piece.

Specifically, a 4+2 erasure coding layout uses four data chunks plus two parity chunks. This configuration tolerates two chunk losses and still rebuilds the original data, which translates to robust protection across three sites and potential site-level failures, while using far less storage than storing three full copies. This makes it well suited for large archives where capacity efficiency matters.

A three-copy replicated scheme would offer good protection, but at a much higher storage cost since it stores three full copies. An EC 2+1 setup provides less fault tolerance (only one chunk loss) and is less protective for across-site failures. Balanced consistency isn’t a protection scheme and doesn’t specify the level of redundancy needed for durability.