# Rolling Update: Minimizing the Impact
+ `PD`
  + Upgrade `followers`
  + Transfer `PD leader`（not relying on `Raft` election timeout）
  + Upgrade the original `leader`
+ `TiKV`
  + Evict `leaders` (avoid election timeout after killing node)
  + Restart


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PD
Online/Offline TiKV
Resource scheduling
Meet the requirement of Raft replicas number
Auto recovery