PXB-3415 [DOC] Release notes for PXB 8.4.0-2 Regular Version

	new file:   docs/release-notes/8.4.0-2.md
	modified:   docs/release-notes/release-notes.md
	modified:   mkdocs-base.yml
	modified:   variables.yml

docs/release-notes/8.4.0-2.md

@@ -0,0 +1,82 @@
+#  Percona XtraBackup 8.4.0-2 (2024-12-16)
+
+Get started with [Quickstart Guide for Percona XtraBackup].
+
+## Release highlights
+
+Percona XtraBackup 8.4.0-2 merges the MySQL 8.4 code base and introduces Percona XtraBackup 8.4.0-2 Pro, in addition to the regular community builds.
+
+Percona XtraBackup 8.4.0-2 Pro build includes the [capabilities](pxb-pro.md#capabilities) that are typically requested by large enterprises. These Pro builds are specifically created and tested by Percona, and the corresponding packages are supported only for Percona customers with a valid subscription.
+
+Percona XtraBackup 8.4.0-2 Pro build includes the [`Reduced backup lock time`](../reduction-in-locks.md) feature. With the addition of the [`--lock-ddl=REDUCED`](./xtrabackup-option-reference.md#lock-ddl) option this feature minimizes the time the server remains locked by xtrabackup during both full and incremental backups. Now, you can execute `Data Definition Language` (DDL) operations while the backup is in progress.
+
+### Benefits
+
+The `--lock-ddl=REDUCED` option features are as follows:
+
+* Acquire and release the backup lock quickly: The backup process minimizes the time it holds the backup lock, allowing for concurrent DDL operations.
+
+    ??? note "Comparing the backup duration with --lock-ddl=REDUCED"
+
+        While we strive to provide accurate performance benchmarks, real-world results may vary depending on your hardware and software configurations.
+
+        The following tables illustrate the approximate time differences between `--lock-ddl=ON` and `--lock-ddl=REDUCED` for local and cloud backups (Amazon S3). The "Improvement (X times)" column shows how many times faster the backup is when using `--lock-ddl=REDUCED` compared to `--lock-ddl=ON`.
+
+        === "Local backup"
+
+	        | Data size in gigabytes | Backup duration with --lock-ddl=ON in seconds| Backup duration with --lock-ddl=REDUCED in seconds| Improvement (X times)  |
+            |-----------------------------|---------------|--------------------|--------------------------|
+            | 50 GB                       | 460.2 sec         | 2.169 sec             | 212.17                   |
+            | 100 GB                      | 901.8 sec        | 1.305 sec             | 691.03                   |
+            | 200 GB                      | 1820.4 sec       | 1.347 sec             | 1351.45                  |
+            | 400 GB                      | 3580.2 sec       | 1.24 sec             | 2887.26                  |
+            | 500 GB                      | 5436 sec         | 1.264 sec             | 4300.63                  |
+
+        === "Cloud (Amazon s3) backup"
+
+            | Data size in gigabytes | Backup duration with --lock-ddl=ON in seconds | Backup duration with --lock-ddl=REDUCED in seconds | Improvement (X times) |
+            |----------------------------|---------------|--------------------|--------------------------|
+            | 50 GB                      | 469.8 sec         | 3.859 sec             | 121.74                   |
+            | 100 GB                     | 927.6 sec         | 4.072 sec             | 227.80                   |
+            | 200 GB                     | 1851.6 sec        | 4.408 sec             | 420.05                   |
+            | 400 GB                     | 3888 sec         | 3.948 sec             | 984.80                   |
+            | 500 GB                     | 4896 sec         | 4.065 sec             | 1204.43                  |
+        
+        Using `--lock-ddl=REDUCED` leads to a dramatic reduction in backup time compared to `--lock-ddl=ON`, especially with larger data sizes.
+
+* Track changes with redo logs: Redo logs record all file-level changes, ensuring data consistency during the backup process.
+* Handle DDL operations: The backup process generates metadata files to account for any DDL operations that occur while the backup is in progress.
+* Ensure consistency: The `--prepare` step processes generated metadata files and uses redo and undo logs to create a consistent database state.
+
+### Limitations
+
+* Certain DDL operations consume significant resources, and xtrabackup simultaneously requires I/O to copy and read files. This requirement can increase resource demand from DDL operations during the backup process.
+
+* The master key rotation with the `ALTER INSTANCE ROTATE INNODB MASTER KEY` is prohibited while backup is in progress.
+
+* Backups may be larger because new `DDL` operations are executed concurrently on the server, and the files generated by the server are included in the backup. Additionally, certain `DDL` operations, such as `ADD INDEX` or encryption changes to existing data files, will cause the data files to be recopied, increasing the backup size.
+
+* The number of open file handles in your operating system should be configured to match the number of files in the server data directory.
+
+* Taking a backup using [page tracking](..//page-tracking.md) is not supported with `--lock-ddl=REDUCED` option.
+
+## Pro Features
+
+[PXB-3269](https://perconadev.atlassian.net/browse/PXB-3269): Reduces the time the server is locked by `xtrabackup` during full and incremental backups.
+
+## Bug fixes
+
+* [PXB-3399](https://perconadev.atlassian.net/browse/PXB-3399): Taking backup on replica faild (Thanks to Hubertus Krogmann
+for reporting this issue.)
+
+* [PXB-3168](https://perconadev.atlassian.net/browse/PXB-3168): Taking backup under high write load faild with `log block numbers mismatch` error.
+
+## Additional resources
+
+Install [Percona XtraBackup 8.4.0-2](..//installation.md)
+
+The [Percona XtraBackup GitHub repository](https://github.com/percona/percona-xtrabackup)
+
+Download product binaries, packages, and tarballs at [Percona Product Downloads](https://www.percona.com/downloads)
+
+[Quickstart Guide for Percona XtraBackup]: ..//quickstart-overview.md

docs/release-notes/release-notes.md

@@ -1,4 +1,6 @@
 # Percona XtraBackup {{vers}} release notes index
 
+* [Percona XtraBackup 8.4.0-2 (2024-12-16)](8.4.0-2.md)
+
 * [Percona XtraBackup 8.4.0-1 (2024-08-20)](8.4.0-1.md)
 

mkdocs-base.yml

@@ -123,7 +123,7 @@ plugins:
   with-pdf: # https://github.com/orzih/mkdocs-with-pdf
           output_path: '_pdf/PerconaXtrabackup-8.2.pdf'
           cover_title: 'Percona XtraBackup Documentation'
-          cover_subtitle: 8.4.0-1 (2024-08-20)
+          cover_subtitle: 8.4.0-2 (2024-12-16)
           author: 'Percona Technical Documentation Team'
           cover_logo: docs/_static/Percona_Logo_Color.png
           debug_html: false
@@ -145,6 +145,7 @@ nav:
   - Home: index.md
   - Release notes:
     - Release notes index: release-notes/release-notes.md
+    - release-notes/8.4.0-2.md
     - release-notes/8.4.0-1.md
   - Quickstart Guide:
       - quickstart-overview.md

variables.yml

@@ -1,8 +1,8 @@
 # variables for HTML output
 
-release: '8.4.0-1'
+release: '8.4.0-2'
 version: '8.4'
 vers: '8.4' # is used in links and to specify a product version
 pkg: 'pxb-84-lts'
-release-date: '2024-08-20'
-title_date: '2024-08-20'
+release-date: '2024-12-16'
+title_date: '2024-12-16'