Who removed it from RAM Make free space for other items?

Couchbase Server
1

If the server determines that a cached item is infrequently used, it removes it from RAM to free space for other items.

from http://docs.couchbase.com/admin/admin/Concepts/concept-cacheLayer.html

Who removed it from RAM Make free space for other items?

2

This is done internally by the server’s KV service. The KV service automatically persists data to disk, and will ‘eject’ less frequently used items when there is memory pressure. It attempts to keep all items in memory.