MySQL 是一個流行的關系型數據庫管理系統，它可以在多臺服務器之間進行數據同步和數據備份。在 MySQL 中 server_id 參數是非常重要的，這個參數在多個 MySQL 實例中保持唯一，以便實現數據同步。

# Example MySQL config file for small systems.
#
# This is for a small system with only a few hundred megabytes of RAM
# where MySQL is only used occasionally, or as a backup for a larger
# installation. Normally you should not need to tune this file.
#
# You need to modify this file for your system.
#
# This file will be read by MySQL server on startup.
#
# Beware that some variables are read-only-properties
# and may not be changed during runtime.
#
# Others are only applicable with the MyISAM engine enabled.
#
# Make sure you familiarize yourself with MySQL for best results.
[mysqld]
# server_id is required for replication. This should be set uniquely for
# each server in a replication group. The default value is 1.
server_id = 1
# Other mysqld options you might tune for your system
max_allowed_packet = 16M
max_heap_table_size = 64M
tmp_table_size = 64M
join_buffer_size = 512K
sort_buffer_size = 512K
read_buffer_size = 512K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 16M
innodb_buffer_pool_size = 128M

如上所示，mysqld 配置文件中的 server_id 參數設置為 1，這個值應該保持唯一。如果您計劃使用 MySQL 復制功能來實現多個服務器之間數據的同步，那么您需要在不同的服務器中配置不同的 server_id 值，以便于 MySQL 實例之間的識別和通信。

無論您是為單個 MySQL 實例配置還是配置用于數據同步的多個實例，都要確保 server_id 在整個環境中的唯一性。