Today we recommend every index to have at least one replica in our
guidelines for designing a resilient cluster. This advice does not apply
to searchable snapshot indices. This commit adjusts the resiliency docs
to account for this. It also slightly adjusts the wording in the
searchable snapshots docs to be more consistent about the distinction
between a "searchable snapshot" and a "searchable snapshot index".
Adds some guidance for designing clusters to be resilient to
failures, including example architectures.
Co-authored-by: James Rodewig <james.rodewig@elastic.co>
Previously, cross-cluster replication (CCR) documentation was located in
the Stack Overview:
https://www.elastic.co/guide/en/elastic-stack-overview/master/xpack-ccr.html
This adds CCR documentation to the Elasticsearch Reference Guide with a
level offset for headings.
The level offset and CCR Stack Overview docs will be removed in later
commits.
