Backend Storage Engine, Storage formats used in Couchbase Server 6.x

Can someone please help me understand

  1. What is the current back end storage engine used in Couchbase Server 6.x enterprise edition? Is it CouchDB based CouchStore or Magma?
  2. What is the current file storage format used by the storage engine? B+ Tree based or an LSM based SSTable format?
  3. What is the compaction strategy used to compact the Couchbase buckets? Is it a Level based or Size based or any other compaction strategy?
  4. What is the index storage format for Global Secondary Indexes in memory and on disk? I understand its Nitro based skip list in memory. What does it look like on disk for data greater than memory scenarios?


  1. Current back end storage engine in Couchbase Server 6.x is CouchStore.
  2. Storage format is B+ Tree.
  3. Compaction strategy is %fragmentation based (hence depends on the write activity of your workload).
  4. Index storage engine is Plasma which is based on skip list in memory. Recommendation is to have at least 20% of your index size available as memory.

Hope that helps.