Migration assistant intro (opensearch-project#8691)

* Migration assistant intro

Signed-off-by: Archer <[email protected]>

* Edit solutions architecture overview.

Signed-off-by: Archer <[email protected]>

* FAQ updates.

Signed-off-by: Archer <[email protected]>

* Add additional edits.

Signed-off-by: Archer <[email protected]>

* Add addtional edits.

Signed-off-by: Archer <[email protected]>

* Apply suggestions from code review

Signed-off-by: Naarcha-AWS <[email protected]>

* Apply suggestions from code review

Signed-off-by: Naarcha-AWS <[email protected]>

* Apply suggestions from code review

Signed-off-by: Naarcha-AWS <[email protected]>

* Update _migrations/index.md

Signed-off-by: Naarcha-AWS <[email protected]>

* Apply suggestions from code review

Signed-off-by: Naarcha-AWS <[email protected]>

* Apply suggestions from code review

Co-authored-by: Nathan Bower <[email protected]>
Signed-off-by: Naarcha-AWS <[email protected]>

* Update is-migration-assistant-right-for-you.md

Signed-off-by: Naarcha-AWS <[email protected]>

* Apply suggestions from code review

Co-authored-by: Nathan Bower <[email protected]>
Signed-off-by: Naarcha-AWS <[email protected]>

* Update _migrations/is-migration-assistant-right-for-you.md

Signed-off-by: Naarcha-AWS <[email protected]>

---------

Signed-off-by: Archer <[email protected]>
Signed-off-by: Naarcha-AWS <[email protected]>
Co-authored-by: Nathan Bower <[email protected]>

_migrations/index.md

@@ -9,51 +9,62 @@ has_toc: false
 
 # Migration Assistant for OpenSearch
 
-This overview outlines the process for successfully performing an end-to-end, zero-downtime migration. The solution offered in this repository caters to several specific scenarios:
+Migration Assistant for OpenSearch aids you in successfully performing an end-to-end, zero-downtime migration to OpenSearch from other search providers. It helps with the following scenarios:
 
-1. **Metadata Migration** - Migrating cluster metadata, such as index settings, aliases, and templates.
-2. **Backfill Migration** - Migrating existing or historical data from a source to a target cluster.
-3. **Live Traffic Migration** - Replicating live ongoing traffic from source to target cluster.
-4. **Comparative Tooling** - Comparing the performance and behaviors of an existing cluster with a prospective new one.
+- **Metadata migration**: Migrating cluster metadata, such as index settings, aliases, and templates.
+- **Backfill migration**: Migrating existing or historical data from a source to a target cluster.
+- **Live traffic migration**: Replicating live ongoing traffic from a source to a target cluster.
+- **Comparative tooling**: Comparing the performance and behaviors of an existing cluster with a prospective new one.
 
-In this guide, we focus on scenarios 1-3, guiding you through a backfill from a source cluster while concurrently handling live production traffic, which will be captured and replayed to a target cluster. 
+This user guide focuses on conducting a comprehensive migration involving both existing and live data with zero downtime and the option to back out of a migration.
 
 It's crucial to note that migration strategies are not universally applicable. This guide provides a detailed methodology, based on certain assumptions detailed throughout, emphasizing the importance of robust engineering practices to ensure a successful migration.
+{: .tip }
 
+## Key components 
 
-## Key Components of the Solution
+The following are the key components of Migration Assistant.
+
+### Elasticsearch/OpenSearch source
 
-### Elasticsearch/OpenSearch Source
 Your source cluster in this solution operates on Elasticsearch or OpenSearch, hosted on EC2 instances or similar computing environments. A proxy is set up to interact with this source cluster, either positioned in front of or directly on the coordinating nodes of the cluster.
 
-### Migration Management Console
+### Migration management console
+
 A console that provides a migration-specific CLI and offers a variety of tools to streamline the migration process.  Everything necessary for completing a migration, other than cleaning up the migration resources, can be done via this Console.
 
-### Traffic Capture Proxy
-This component is designed for HTTP RESTful traffic, playing a dual role. It not only forwards traffic to the source cluster but also splits and channels this traffic to a stream-processing service for later playback.
+### Traffic capture proxy
+
+This component is designed for HTTP RESTful traffic. It forwards traffic to the source cluster and also splits and channels this traffic to a stream processing service for later playback.
 
 ### Traffic Replayer
+
 Acting as a traffic simulation tool, the Traffic Replayer replays recorded request traffic to a target cluster, mirroring source traffic patterns. It links original requests and their responses to those directed at the target cluster, facilitating comparative analysis.
 
-### Metadata Migration Tool
-A tool integrated into the Migration CLI that can also be used independently to migrate cluster metadata, including index mappings, index configuration settings, templates, component templates, and aliases.
+### Metadata migration tool
 
-### Reindex-from-Snapshot
-Reindexing data from an existing snapshot on Elastic Container Service (ECS) workers that coordinate the migration of documents from an existing snapshot, reindexing the documents in parallel to a target cluster.
+The Metadata migration tool integrated into the Migration CLI can be used independently to migrate cluster metadata, including index mappings, index configuration settings, templates, component templates, and aliases.
+
+### reindex-from-snapshot
+
+`Reindex-from-Snapshot` (RFS) reindexes data from an existing snapshot. Workers on Amazon Elastic Container Service (Amazon ECS) coordinate the migration of documents from an existing snapshot, reindexing the documents in parallel to a target cluster.
+
+### Target cluster
 
-### Target Cluster
 The destination cluster for migration or comparison in an A/B test.
 
-### Architecture Overview
-This architecture is based on the use of AWS cloud infrastructure, but most tools are designed to be cloud-independent. A local containerized version of this solution is also available.
+### Architecture overview
+
+The Migration Assistant architecture is based on the use of an AWS Cloud infrastructure, but most tools are designed to be cloud independent. A local containerized version of this solution is also available.
 
 The design deployed in AWS is as follows: 
 
 ![Migration architecture overview]({{site.url}}{{site.baseurl}}/images/migrations/migration-architecture-overview.svg)
 
 1. Client traffic is directed to the existing cluster.
-2. An ALB with Capture Proxies relaying traffic to source while replicating to Amazon MSK.
-3. With continuous traffic capture in place, a Reindex-from-Snapshot (RFS) is initiated by the user via Migration Console.
-4. Once Reindex-from-Snapshot is complete, traffic captured is replayed from MSK by Traffic Replayer.
-5. Performance and behavior of traffic sent to source and target clusters are compared by reviewing logs and metrics.
-6. After confirming the target cluster’s functionality meets expectations the use redirects clients to new target.
+2. An Application Load Balancer with capture proxies relays traffic to a source while replicating data to Amazon Managed Streaming for Apache Kafka (Amazon MSK).
+3. Using the migration console, you can initiate metadata migration to establish indexes, templates, component templates, and aliases on the target cluster.
+4. With continuous traffic capture in place, you can use a `reindex-from-snapshot` process to capture data from your current index.
+4. Once `reindex-from-snapshot` is complete, captured traffic is replayed from Amazon MSK to the target cluster by the traffic replayer.
+5. Performance and behavior of traffic sent to the source and target clusters are compared by reviewing logs and metrics.
+6. After confirming that the target cluster's functionality meets expectations, clients are redirected to the new target.