Merge remote-tracking branch 'upstream/master' into add-8.3-rn

br/br-snapshot-guide.md

@@ -68,6 +68,7 @@ The output is as follows, corresponding to the physical time `2022-09-08 13:30:0
 > - Starting from BR v7.6.0, to address potential restore bottlenecks in scenarios with large-scale Regions, BR supports accelerating restore through the coarse-grained Region scattering algorithm (experimental). You can enable this feature by specifying the command-line parameter `--granularity="coarse-grained"`.
 > - Starting from BR v8.0.0, the snapshot restore through the coarse-grained Region scattering algorithm is generally available (GA) and enabled by default. BR improves the snapshot restore speed significantly by implementing various optimizations such as adopting the coarse-grained Region scattering algorithm, creating databases and tables in batches, reducing the mutual impact between SST file downloads and ingest operations, and accelerating the restore of table statistics. According to test results from real-world cases, the SST file download speed for snapshot restore is improved by approximately up to 10 times, the data restore speed per TiKV node stabilizes at 1.2 GiB/s, the end-to-end restore speed is improved by approximately 1.5 to 3 times, and 100 TiB of data can be restored within one hour.
 > - Starting from BR v8.2.0, the command line parameter `--granularity` is deprecated, and the coarse-grained Region scattering algorithm is enabled by default.
+> - Starting from BR v8.3.0, the snapshot restore task introduces available disk space checks for TiKV and TiFlash: at the beginning of the task, BR verifies whether TiKV and TiFlash have sufficient disk space based on the size of SST files to be restored; for TiKV v8.3.0 or later version, TiKV verifies whether it has sufficient disk space before downloading each SST file. If the space is insufficient according to any of these checks, the restore task fails with an error. You can skip the check at the beginning of the restore task by setting `--check-requirements=false`, but the disk space check before TiKV downloads each SST file cannot be skipped.
 
 You can restore a snapshot backup by running the `tiup br restore full` command. Run `tiup br restore full --help` to see the help information:
 

system-variables.md

@@ -3007,9 +3007,14 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
 - Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No
 - Type: Integer
 - Default value: `-1`
-- Range: `[1, 256]`
+- Range: `-1` or `[1, 256]`
 - Unit: Threads
-- Specifies the number of threads in the [Resolve Locks](/garbage-collection-overview.md#resolve-locks) step of GC. A value of `-1` means that TiDB will automatically decide the number of garbage collection threads to use.
+- This variable controls the number of concurrent threads during the [Resolve Locks](/garbage-collection-overview.md#resolve-locks) step of the [Garbage Collection (GC)](/garbage-collection-overview.md) process.
+- Starting from v8.3.0, this variable also controls the number of concurrent threads during the [Delete Ranges](/garbage-collection-overview.md#delete-ranges) step of the GC process.
+- By default, this variable is `-1`, allowing TiDB to automatically determine the appropriate number of threads based on workloads.
+- When this variable is set to a number in the range of `[1, 256]`:
+    - Resolve Locks directly uses the value set for this variable as the number of threads.
+    - Delete Range uses one-fourth of the value set for this variable as the number of threads.
 
 ### tidb_gc_enable <span class="version-mark">New in v5.0</span>