Create documentation for snapshots with hashed prefix path type (#8196)

* Create documentation for snapshots with hashed prefix path type

Signed-off-by: Ashish Singh <ssashish@amazon.com>

* Add documentation on new cluster settings for fixed prefix

Signed-off-by: Ashish Singh <ssashish@amazon.com>

* Update create-repository.md

* Update create-repository.md

* Apply suggestions from code review

Signed-off-by: Naarcha-AWS <97990722+Naarcha-AWS@users.noreply.github.com>

* Apply suggestions from code review

Signed-off-by: Naarcha-AWS <97990722+Naarcha-AWS@users.noreply.github.com>

* Apply suggestions from code review

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

---------

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

_api-reference/snapshots/create-repository.md

@@ -43,6 +43,15 @@ The following table lists parameters that can be used with both the `fs` and `s3
 Request field | Description
 :--- | :---
 `prefix_mode_verification` | When enabled, adds a hashed value of a random seed to the prefix for repository verification. For remote-store-enabled clusters, you can add the `setting.prefix_mode_verification` setting to the node attributes for the supplied repository. This field works with both new and existing repositories. Optional.
+`shard_path_type` | Controls the path structure of shard-level blobs. Supported values are `FIXED`, `HASHED_PREFIX`, and `HASHED_INFIX`. For more information about each value, see [shard_path_type values](#shard_path_type-values)/. Default is `FIXED`. Optional.
+
+#### shard_path_type values
+
+The following values are supported in the `shard_path_type` setting:
+
+- `FIXED`: Keeps the path structure in the existing hierarchical manner, such as `<ROOT>/<BASE_PATH>/indices/<index-id>/0/<SHARD_BLOBS>`.
+- `HASHED_PREFIX`: Prepends a hashed prefix at the start of the path for each unique shard ID, for example, `<ROOT>/<HASH-OF-INDEX-ID-AND-SHARD-ID>/<BASE_PATH>/indices/<index-id>/0/<SHARD_BLOBS>`.
+- `HASHED_INFIX`: Appends a hashed prefix after the base path for each unique shard ID, for example, `<ROOT>/<BASE-PATH>/<HASH-OF-INDEX-ID-AND-SHARD-ID>/indices/<index-id>/0/<SHARD_BLOBS>`. The hash method used is `FNV_1A_COMPOSITE_1`, which uses the `FNV1a` hash function and generates a custom-encoded 64-bit hash value that scales well with most remote store options. `FNV1a` takes the most significant 6 bits to create a URL-safe Base64 character and the next 14 bits to create a binary string.
 
 ### fs repository
 

_install-and-configure/configuring-opensearch/index-settings.md

@@ -73,6 +73,12 @@ OpenSearch supports the following dynamic cluster-level index settings:
 
 - `cluster.remote_store.segment.transfer_timeout` (Time unit): Controls the maximum amount of time to wait for all new segments to update after refresh to the remote store. If the upload does not complete within a specified amount of time, it throws a `SegmentUploadFailedException` error. Default is `30m`. It has a minimum constraint of `10m`.
 
+- `cluster.remote_store.translog.path.prefix` (String): Controls the fixed path prefix for translog data on a remote-store-enabled cluster. This setting only applies when the `cluster.remote_store.index.path.type` setting is either `HASHED_PREFIX` or `HASHED_INFIX`. Default is an empty string, `""`.
+
+- `cluster.remote_store.segments.path.prefix` (String): Controls the fixed path prefix for segment data on a remote-store-enabled cluster. This setting only applies when the `cluster.remote_store.index.path.type` setting is either `HASHED_PREFIX` or `HASHED_INFIX`. Default is an empty string, `""`.
+
+- `cluster.snapshot.shard.path.prefix` (String): Controls the fixed path prefix for snapshot shard-level blobs. This setting only applies when the repository `shard_path_type` setting is either `HASHED_PREFIX` or `HASHED_INFIX`. Default is an empty string, `""`.
+
 ## Index-level index settings
 
 You can specify index settings at index creation. There are two types of index settings: