br restore failed due to "split region failed"

[fubinzh]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. Create a TiDB cluster with 20 TiKVs (16c64g)
2. run br restore

2. What did you expect to see? (Required)

Br restore should succeed

3. What did you see instead (Required)

Br restore failed

4. What is your TiDB version? (Required)

[root@br-0 tmp]# /br-no-limit -V                           
Release Version: v7.6.0-alpha-727-g40c77af-dirty           
Git Commit Hash: 40c77afaa130697b197c44181facb3621b406816  
Git Branch: forbidden_cache_from_statistic_and_coprocessor 
Go Version: go1.21.6                                       
UTC Build Time: 2024-01-16 08:23:31                        
Race Enabled: false                                                                             

[fubinzh]

/component br
/severity critical

[Leavrth]

#50477

[3pointer]

close it due to duplicate with #50477