When you apply rolling updates to the TiDB services, the running application is affected to varying degrees. Therefore, it is not recommended that you perform a rolling update during business peak hours. You need to configure the minimum cluster topology (TiDB * 2, PD * 3, TiKV * 3). If the Pump or Drainer service is involved in the cluster, it is recommended to stop Drainer before rolling updates. When you upgrade TiDB, Pump is also upgraded.