Add qat_zstd as a valid index.codec value. (#12000)

* Add qat_zstd as a valid index.codec value.

Signed-off-by: Mulugeta Mammo <mulugeta.mammo@intel.com>

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

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>
Signed-off-by: mulugetam <mulugeta.mammo@intel.com>

* Update _im-plugin/index-codecs.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>
Signed-off-by: mulugetam <mulugeta.mammo@intel.com>

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

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>
Signed-off-by: mulugetam <mulugeta.mammo@intel.com>

---------

Signed-off-by: Mulugeta Mammo <mulugeta.mammo@intel.com>
Signed-off-by: mulugetam <mulugeta.mammo@intel.com>
Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

Author: mulugetam

_im-plugin/index-codecs.md

@@ -37,11 +37,12 @@ As of OpenSearch 2.15, hardware-accelerated compression codecs for the `DEFLATE`
 The new hardware-accelerated codecs can be used by setting one of the following `index.codec` values:
 * `qat_lz4` (OpenSearch 2.15 and later): Hardware-accelerated `LZ4`
 * `qat_deflate` (OpenSearch 2.15 and later): Hardware-accelerated `DEFLATE`
+* `qat_zstd` (OpenSearch 2.19.3 and later): Hardware-accelerated `ZSTD`
 
-`qat_deflate` offers a much better compression ratio than `qat_lz4`, with a modest drop in compression and decompression speed.
+`qat_deflate` offers a much better compression ratio than `qat_lz4`, with a modest drop in compression and decompression speed. `qat_zstd` uses hardware acceleration for compression but relies on software-based decompression.
 {: .note}
 
-The `index.codec.compression_level` setting can be used to specify the compression level for both `qat_lz4` and `qat_deflate`. 
+The `index.codec.compression_level` setting can be used to specify the compression level for both `qat_lz4`, `qat_deflate`, and `qat_zstd`. 
 
 The `index.codec.qatmode` setting controls the behavior of the hardware accelerator and uses one of the following values:
 

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

@@ -149,12 +149,13 @@ OpenSearch supports the following static index-level index settings:
     - `zstd_no_dict`(OpenSearch 2.9 and later)
     - `qat_lz4` (OpenSearch 2.14 and later, on supported systems)
     - `qat_deflate` (OpenSearch 2.14 and later, on supported systems)
+    - `qat_zstd` (OpenSearch 2.19.3 and later, on supported systems)
 
-For `zstd`, `zstd_no_dict`, `qat_lz4`, and `qat_deflate`, you can specify the compression level in the `index.codec.compression_level` setting. For more information, see [Index codec settings]({{site.url}}{{site.baseurl}}/im-plugin/index-codecs/). Optional. Default is `default`.
+For `zstd`, `zstd_no_dict`, `qat_lz4`, `qat_deflate`, and `qat_zstd`, you can specify the compression level in the `index.codec.compression_level` setting. For more information, see [Index codec settings]({{site.url}}{{site.baseurl}}/im-plugin/index-codecs/). Optional. Default is `default`.
 
-- `index.codec.compression_level` (Integer): The compression level setting provides a trade-off between compression ratio and speed. A higher compression level results in a higher compression ratio (smaller storage size), but slower compression and decompression speeds lead to higher indexing and search latencies. This setting can only be specified if `index.codec` is set to `zstd` and `zstd_no_dict` in OpenSearch 2.9 and later or `qat_lz4` and `qat_deflate` in OpenSearch 2.14 and later. Valid values are integers in the [1, 6] range. For more information, see [Index codec settings]({{site.url}}{{site.baseurl}}/im-plugin/index-codecs/). Optional. Default is 3.
+- `index.codec.compression_level` (Integer): The compression level setting provides a trade-off between compression ratio and speed. A higher compression level results in a higher compression ratio (smaller storage size), but slower compression and decompression speeds lead to higher indexing and search latencies. This setting can only be specified if `index.codec` is set to `zstd` or `zstd_no_dict` in OpenSearch 2.9 and later; `qat_lz4` or `qat_deflate` in OpenSearch 2.14 and later; or `qat_zstd` in OpenSearch 2.19.3 and later. Valid values are integers in the `[1, 6]` range. For more information, see [Index codec settings]({{site.url}}{{site.baseurl}}/im-plugin/index-codecs/). Optional. Default is `3`.
 
-- `index.codec.qatmode` (String): The hardware acceleration mode used for the `qat_lz4` and `qat_deflate` compression codecs. Valid values are `auto` and `hardware`. For more information, see [Index codec settings]({{site.url}}{{site.baseurl}}/im-plugin/index-codecs/). Optional. Default is `auto`. 
+- `index.codec.qatmode` (String): The hardware acceleration mode used for the `qat_lz4`, `qat_deflate`, and `qat_zstd` compression codecs. Valid values are `auto` and `hardware`. For more information, see [Index codec settings]({{site.url}}{{site.baseurl}}/im-plugin/index-codecs/). Optional. Default is `auto` (the recommended setting). 
 
 - `index.routing_partition_size` (Integer): The number of shards a custom routing value can go to. Routing helps an imbalanced cluster by relocating values to a subset of shards rather than a single shard. To enable routing, set this value to greater than 1 but less than `index.number_of_shards`. Default is 1.