This is an automated cherry-pick of pingcap#21217

Signed-off-by: ti-chi-bot <[email protected]>

Author: qiancai

storage-engine/titan-configuration.md

@@ -118,7 +118,15 @@ To disable Titan, you can configure the `rocksdb.defaultcf.titan.blob-run-mode`
 - When the option is set to `read-only`, all newly written values are written into RocksDB, regardless of the value size.
 - When the option is set to `fallback`, all newly written values are written into RocksDB, regardless of the value size. Also, all compacted values stored in the Titan blob file are automatically moved back to RocksDB.
 
+<<<<<<< HEAD
 To disable Titan, perform the following steps:
+=======
+To disable Titan for all existing and future data, you can take the following steps. Note that you can skip Step 2 because it greatly affects online traffic performance. In fact even without Step 2, the data compaction consumes extra I/O and CPU resources when it moves data from Titan to RocksDB, and performance will degrade (sometimes as much as 50%) when TiKV I/O or CPU resources are limited.
+
+> **Warning:**
+>
+> When disabling Titan for TiDB versions earlier than v8.5.0, it is not recommended to modify the TiKV configuration item [`rocksdb.titan.enabled`](/tikv-configuration-file.md#enabled) to `false`, as this might cause TiKV to crash. Following Step 1 is sufficient to disable Titan.
+>>>>>>> 445dea0c18 (titan-configuration: remove the unrecommended steps of updating TiKV configuration  (#21217))
 
 1. Update the configuration file of the TiKV nodes you wish to disable Titan for and restart TiKV:
 
@@ -137,6 +145,7 @@ To disable Titan, perform the following steps:
 
 3. After the compaction is finished, wait until the **Blob file count** metrics under **TiKV-Details/Titan - kv** decrease to `0`.
 
+<<<<<<< HEAD
 4. Update the configuration of these TiKV nodes to disable Titan.
 
     ```toml
@@ -148,6 +157,8 @@ To disable Titan, perform the following steps:
 >
 > Disabling Titan is an experimental feature. It is **NOT** recommended to use it if not necessary.
 
+=======
+>>>>>>> 445dea0c18 (titan-configuration: remove the unrecommended steps of updating TiKV configuration  (#21217))
 ## Level Merge (experimental)
 
 In TiKV 4.0, [Level Merge](/storage-engine/titan-overview.md#level-merge), a new algorithm, is introduced to improve the performance of range query and to reduce the impact of Titan GC on the foreground write operations. You can enable Level Merge using the following option:

tikv-configuration-file.md

@@ -1156,8 +1156,23 @@ Configuration items related to Titan.
 
 ### `enabled`
 
+<<<<<<< HEAD
 + Enables or disables Titan
 + Default value: `false`
+=======
+> **Warning**
+>
+> When disabling Titan for TiDB versions earlier than v8.5.0, it is not recommended to modify this configuration item to `false`, as this might cause TiKV to crash. To disable Titan, refer to the steps in [Disable Titan](/storage-engine/titan-configuration.md#disable-titan).
+
+> **Note:**
+>
+> - To enhance the performance of wide table and JSON data writing and point query, starting from TiDB v7.6.0, the default value changes from `false` to `true`, which means that Titan is enabled by default.
+> - Existing clusters upgraded to v7.6.0 or later versions retain the original configuration, which means that if Titan is not explicitly enabled, it still uses RocksDB.
+> - If the cluster has enabled Titan before upgrading to TiDB v7.6.0 or later versions, Titan will be retained after the upgrade, and the [`min-blob-size`](/tikv-configuration-file.md#min-blob-size) configuration before the upgrade will be retained. If you do not explicitly configure the value before the upgrade, the default value of the previous version `1KiB` will be retained to ensure the stability of the cluster configuration after the upgrade.
+
++ Enables or disables Titan.
++ Default value: `true`
+>>>>>>> 445dea0c18 (titan-configuration: remove the unrecommended steps of updating TiKV configuration  (#21217))
 
 ### `dirname`