Add migration phases pages (#8828)

* Add first three migration phases pages

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* Apply suggestions from code review

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* Add backfill page.

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* Update backfill.md

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* Add replayer page.

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* Fix grammar.

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* Add final migration phases page.

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* Apply suggestions from code review

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* Apply suggestions from code review

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* Update _migrations/migration-phases/verifying-tools-for-migration.md

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* Update _migrations/migration-phases/backfill.md

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* Add migration phase links

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* Edit migration console section

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* Apply suggestions from code review

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* Update migrating-metadata.md

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* Apply suggestions from code review

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* Rename traffic replacer.

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* Update _migrations/migration-phases/verifying-tools-for-migration.md

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* Add sentence about live traffic capture

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* Apply suggestions from code review

Co-authored-by: Nathan Bower <nbower@amazon.com>
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* Update _migrations/migration-phases/backfill.md

Co-authored-by: Nathan Bower <nbower@amazon.com>
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* Update _migrations/migration-phases/verifying-tools-for-migration.md

Co-authored-by: Nathan Bower <nbower@amazon.com>
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* Update _migrations/migration-phases/verifying-tools-for-migration.md

Co-authored-by: Nathan Bower <nbower@amazon.com>
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* Add editorial review.

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* Additional editorial comments.

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* Editorial for infra and traffic

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* Editorial comments for using traffic replayer.

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* Add final editorial comments.

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* Apply suggestions from code review

Co-authored-by: Nathan Bower <nbower@amazon.com>
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---------

Signed-off-by: Archer <naarcha@amazon.com>
Signed-off-by: Naarcha-AWS <97990722+Naarcha-AWS@users.noreply.github.com>
Co-authored-by: Nathan Bower <nbower@amazon.com>

_migrations/getting-started-data-migration.md

@@ -181,7 +181,7 @@ To deploy Migration Assistant, use the following steps:
 These commands deploy the following stacks:
 
 * Migration Assistant network stack
-* Reindex From Snapshot stack
+* `Reindex-from-snapshot` stack
 * Migration console stack
 
 ---
@@ -253,7 +253,7 @@ Run the following command to migrate metadata:
 console metadata migrate [...]
 ```
 
-For more information, see [Metadata migration].
+For more information, see [Migrating metadata]({{site.url}}{{site.baseurl}}/migrations/migration-phases/migrating-metadata/).
 
 ---
 
@@ -285,7 +285,7 @@ You can now use RFS to migrate documents from your original cluster:
     console backfill stop
     ```
 
-For more information, see [Backfill execution].
+For more information, see [Backfill]({{site.url}}{{site.baseurl}}/migrations/migration-phases/backfill/).
 
 ---
 
@@ -328,4 +328,3 @@ fields @message
 
 If any failed documents are identified, you can index the failed documents directly as opposed to using RFS.
 
-For more information, see [Backfill migration].

_migrations/migration-console/accessing-the-migration-console.md

@@ -1,12 +1,15 @@
+---
+layout: default
+title: Accessing the migration console
+nav_order: 35
+parent: Migration console
+---
 
+# Accessing the migration console
 
+The Bootstrap box deployed through Migration Assistant contains a script that simplifies access to the migration console through that instance.
 
-The Migrations Assistant deployment includes an ECS task that hosts tools to run different phases of the migration and check the progress or results of the migration.
-
-## SSH into the Migration Console
-Following the AWS Solutions deployment, the bootstrap box contains a script that simplifies access to the migration console through that instance.
-
-To access the Migration Console, use the following commands:
+To access the migration console, use the following commands:
 
 ```shell
 export STAGE=dev
@@ -16,13 +19,7 @@ export AWS_REGION=us-west-2
 
 When opening the console a message will appear above the command prompt, `Welcome to the Migration Assistant Console`.
 
-<details>
-
-<summary>
-<b>SSH from any machine into Migration Console</b>
-</summary>
-
-On a machine with the [AWS CLI](https://docs.aws.amazon.com/cli/latest/userguide/getting-started-install.html) ↗ and the [AWS Session Manager Plugin](https://docs.aws.amazon.com/systems-manager/latest/userguide/session-manager-working-with-install-plugin.html) ↗, you can directly connect to the migration console. Ensure you've run `aws configure` with credentials that have access to the environment.
+On a machine with the [AWS Command Line Interface (AWS CLI)](https://docs.aws.amazon.com/cli/latest/userguide/getting-started-install.html) and the [AWS Session Manager plugin](https://docs.aws.amazon.com/systems-manager/latest/userguide/session-manager-working-with-install-plugin.html), you can directly connect to the migration console. Ensure that you've run `aws configure` with credentials that have access to the environment.
 
 Use the following commands:
 
@@ -32,10 +29,6 @@ export SERVICE_NAME=migration-console
 export TASK_ARN=$(aws ecs list-tasks --cluster migration-${STAGE}-ecs-cluster --family "migration-${STAGE}-${SERVICE_NAME}" | jq --raw-output '.taskArns[0]')
 aws ecs execute-command --cluster "migration-${STAGE}-ecs-cluster" --task "${TASK_ARN}" --container "${SERVICE_NAME}" --interactive --command "/bin/bash"
 ```
-</details>
-
-## Troubleshooting
 
-### Deployment Stage
 
-Typically, `STAGE` is `dev`, but this may vary based on what the user specified during deployment.
+Typically, `STAGE` is equivalent to a standard `dev` environment, but this may vary based on what the user specified during deployment.

_migrations/migration-console/index.md

@@ -3,4 +3,9 @@ layout: default
 title: Migration console
 nav_order: 30
 has_children: true
----
+---
+
+The Migrations Assistant deployment includes an Amazon Elastic Container Service (Amazon ECS) task that hosts tools that run different phases of the migration and check the progress or results of the migration. This ECS task is called the **migration console**. The migration console is a command line interface used to interact with the deployed components of the solution.
+
+This section provides information about how to access the migration console and what commands are supported.
+

_migrations/migration-console/migration-console-commands-references.md

@@ -1,83 +1,106 @@
+---
+layout: default
+title: Command reference
+nav_order: 35
+parent: Migration console
+---
 
 
+# Migration console command reference
 
-The Migration Assistant Console is a command line interface to interact with the deployed components of the solution.
+Migration console commands follow this syntax: `console [component] [action]`. The components include `clusters`, `backfill`, `snapshot`, `metadata`, and `replay`. The console is configured with a registry of the deployed services and the source and target cluster, generated from the `cdk.context.json` values.
 
-The commands are in the form of `console [component] [action]`. The components include `clusters`, `backfill` (e.g the Reindex from Snapshot service), `snapshot`, `metadata`, `replay`, etc. The console is configured with a registry of the deployed services and the source and target cluster, generated from the `cdk.context.json` values.
-
-## Commonly Used Commands
+## Commonly used commands
 
 The exact commands used will depend heavily on use-case and goals, but the following are a series of common commands with a quick description of what they do.
 
+### Check connection
+
+Reports whether both the source and target clusters can be reached and provides their versions.
+
 ```sh
 console clusters connection-check
 ```
-Reports whether both the source and target clusters can be reached and their versions.
 
+### Run `cat-indices`
+
+Runs the `cat-indices` API on the cluster.
 
 ```sh
 console clusters cat-indices
 ```
-Runs the `_cat/indices` command on each cluster and prints the results.
 
-***
+### Create a snapshot
+
+Creates a snapshot of the source cluster and stores it in a preconfigured Amazon Simple Storage Service (Amazon S3) bucket.
 
 ```sh
 console snapshot create
 ```
-Initiates creating a snapshot on the source cluster, into a pre-configured S3 bucket.
+
+## Check snapshot status
+
+Runs a detailed check on the snapshot creation status, including estimated completion time:
 
 ```sh
 console snapshot status --deep-check
 ```
-Runs a detailed check on the status of the snapshot creation, including estimated completion time.
 
-***
+## Evaluate metadata
+
+Performs a dry run of metadata migration, showing which indexes, templates, and other objects will be migrated to the target cluster.
 
 ```sh
 console metadata evaluate
 ```
-Perform a dry run of metadata migration, showing which indices, templates, and other objects will be migrated to the target cluster.
+
+## Migrate metadata
+
+Migrates the metadata from the source cluster to the target cluster.
 
 ```sh
 console metadata migrate
 ```
-Perform an actual metadata migration.
 
-***
+## Start a backfill
 
-```sh
-console backfill start
-```
-If the Reindex From Snapshot service is enabled, start an instance of the service to begin moving documents to the target cluster.
+If `Reindex-From-Snapshot` (RFS) is enabled, this command starts an instance of the service to begin moving documents to the target cluster:
 
 There are similar `scale UNITS` and `stop` commands to change the number of active instances for RFS.
 
+
 ```sh
-console backfill status --deep-check
+console backfill start
 ```
-See the current status of the backfill migration, with the number of instances operating and the progress of the shards.
 
-***
+## Check backfill status
+
+Gets the current status of the backfill migration, including the number of operating instances and the progress of the shards.
+
+
+## Start Traffic Replayer
+
+If Traffic Replayer is enabled, this command starts an instance of Traffic Replayer to begin replaying traffic against the target cluster.
+The `stop` command stops all active instances.
 
 ```sh
 console replay start
 ```
-If the Traffic Replayer service is enabled, start an instance of the service to begin replaying traffic against the target cluster.
-The `stop` command stops all active instances.
 
-***
+## Read logs
+
+Reads any logs that exist when running Traffic Replayer. Use tab completion on the path to fill in the available `NODE_IDs` and, if applicable, log file names. The tuple logs roll over at a certain size threshold, so there may be many files named with timestamps. The `jq` command pretty-prints each line of the tuple output before writing it to file.
 
 ```sh
 console tuples show --in /shared-logs-output/traffic-replayer-default/[NODE_ID]/tuples/console.log | jq > readable_tuples.json
 ```
-Use tab completion on the path to fill in the available node ids and, if applicable, log file names. The tuples logs roll over at a certain size threshold, so there may be many files named with timestamps. The `jq` command pretty-prints each line of the tuple output before writing it to file.
 
 
-## Command Reference
-All commands and options can be explored within the tool itself by using the `--help` option, either for the entire `console` application or for individual components (e.g. `console backfill --help`). The console also has command autocomplete set up to assist with usage.
+## Help command
 
-```
+All commands and options can be explored within the tool itself by using the `--help` option, either for the entire `console` application or for individual components (for example, `console backfill --help`). For example:
+
+```bash
 $ console --help
 Usage: console [OPTIONS] COMMAND [ARGS]...
 

_migrations/migration-phases/assessing-your-cluster-for-migration.md

@@ -0,0 +1,44 @@
+---
+layout: default
+title: Assessing your cluster for migration
+nav_order: 60
+has_children: true
+parent: Migration phases
+---
+
+# Assessing your cluster for migration
+
+The goal of Migration Assistant is to streamline the process of migrating from one location or version of Elasticsearch/OpenSearch to another. However, completing a migration sometimes requires resolving client compatibility issues before they can communicate directly with the target cluster.
+
+## Understanding breaking changes
+
+Before performing any upgrade or migration, you should review any breaking changes documentation. Even if the cluster is migrated, there may be changes required in order for clients to connect to the new cluster.
+
+## Upgrade and breaking changes guides
+
+For migration paths between Elasticsearch 6.8 and OpenSearch 2.x, you should be familiar with the following documentation, depending on your specific use case:
+
+* [Upgrading Amazon OpenSearch Service domains](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/version-migration.html).
+
+* [Amazon OpenSearch Service rename - Summary of changes](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/rename.html).
+
+* [OpenSearch breaking changes](https://opensearch.org/docs/latest/breaking-changes/).
+
+The next step is to set up a proper test bed to verify that your applications will work as expected on the target version.
+
+## Impact of data transformations
+
+Any time you apply a transformation to your data, such as changing index names, modifying field names or field mappings, or splitting indexes with type mappings, these changes may need to be reflected in your client configurations. For example, if your clients are reliant on specific index or field names, you must ensure that their queries are updated accordingly. 
+
+
+
+We recommend running production-like queries against the target cluster before switching to actual production traffic. This helps verify that the client can:
+
+- Communicate with the target cluster.
+- Locate the necessary indexes and fields.
+- Retrieve the expected results.
+
+For complex migrations involving multiple transformations or breaking changes, we highly recommend performing a trial migration with representative, non-production data (for example, in a staging environment) to fully test client compatibility with the target cluster.
+
+
+