I want to use the Legacy Search option in Retain 4. Does it do its searches off of the old Retain 3 index in the /index directory?
No. The Legacy Search only uses the old indexer until the migration of all messages to the new Retain 4 format. Once the migration has completed, the old search engine gets shut down and any searches performed in the Legacy Search tab will use the new search engine/indexes.
This article was originally published in the GWAVA knowledgebase as article ID 2767.