diff --git a/ocaml/xapi/xapi_cluster_helpers.ml b/ocaml/xapi/xapi_cluster_helpers.ml
index 31a655a3e7..f7ea78eab9 100644
--- a/ocaml/xapi/xapi_cluster_helpers.ml
+++ b/ocaml/xapi/xapi_cluster_helpers.ml
@@ -114,7 +114,7 @@ let corosync3_enabled ~__context =
   let restrictions = Db.Pool.get_restrictions ~__context ~self:pool in
   List.assoc_opt "restrict_corosync3" restrictions = Some "false"
 
-let maybe_generate_alert ~__context ~num_hosts ~missing_hosts ~new_hosts ~quorum
+let maybe_generate_alert ~__context ~num_hosts ~hosts_left ~hosts_joined ~quorum
     =
   let generate_alert join cluster_host =
     let host = Db.Cluster_host.get_host ~__context ~self:cluster_host in
@@ -148,10 +148,10 @@ let maybe_generate_alert ~__context ~num_hosts ~missing_hosts ~new_hosts ~quorum
     )
   in
   if cluster_health_enabled ~__context then (
-    List.iter (generate_alert false) missing_hosts ;
-    List.iter (generate_alert true) new_hosts ;
+    List.iter (generate_alert false) hosts_left ;
+    List.iter (generate_alert true) hosts_joined ;
     (* only generate this alert when the number of hosts is decreasing *)
-    if missing_hosts <> [] && num_hosts <= quorum then
+    if hosts_left <> [] && num_hosts <= quorum then
       let pool = Helpers.get_pool ~__context in
       let pool_uuid = Db.Pool.get_uuid ~__context ~self:pool in
       let name, priority = Api_messages.cluster_quorum_approaching_lost in
diff --git a/ocaml/xapi/xapi_cluster_host.ml b/ocaml/xapi/xapi_cluster_host.ml
index 78c943e18a..fcf7c7c79e 100644
--- a/ocaml/xapi/xapi_cluster_host.ml
+++ b/ocaml/xapi/xapi_cluster_host.ml
@@ -13,7 +13,6 @@
  *)
 
 open Xapi_clustering
-open Xapi_cluster_helpers
 open Ipaddr_rpc_type
 
 module D = Debug.Make (struct let name = "xapi_cluster_host" end)
@@ -55,20 +54,6 @@ let call_api_function_with_alert ~__context ~msg ~cls ~obj_uuid ~body
         raise err
   )
 
-let alert_for_cluster_host ~__context ~cluster_host ~missing_hosts ~new_hosts =
-  let num_hosts = Db.Cluster_host.get_all ~__context |> List.length in
-  let cluster = Db.Cluster_host.get_cluster ~__context ~self:cluster_host in
-  let quorum = Db.Cluster.get_quorum ~__context ~self:cluster |> Int64.to_int in
-  maybe_generate_alert ~__context ~missing_hosts ~new_hosts ~num_hosts ~quorum
-
-let alert_for_cluster_host_leave ~__context ~cluster_host =
-  alert_for_cluster_host ~__context ~cluster_host ~missing_hosts:[cluster_host]
-    ~new_hosts:[]
-
-let alert_for_cluster_host_join ~__context ~cluster_host =
-  alert_for_cluster_host ~__context ~cluster_host ~missing_hosts:[]
-    ~new_hosts:[cluster_host]
-
 (* Create xapi db object for cluster_host, resync_host calls clusterd *)
 let create_internal ~__context ~cluster ~host ~pIF : API.ref_Cluster_host =
   with_clustering_lock __LOC__ (fun () ->
@@ -81,7 +66,6 @@ let create_internal ~__context ~cluster ~host ~pIF : API.ref_Cluster_host =
         ~enabled:false ~current_operations:[] ~allowed_operations:[]
         ~other_config:[] ~joined:false ~live:false
         ~last_update_live:API.Date.epoch ;
-      alert_for_cluster_host_join ~__context ~cluster_host:ref ;
       ref
   )
 
@@ -273,16 +257,21 @@ let destroy_op ~__context ~self ~force =
           (Cluster_client.LocalClient.leave, "destroy")
       in
       let result = local_fn (rpc ~__context) dbg in
+      let cluster = Db.Cluster_host.get_cluster ~__context ~self in
       match Idl.IdM.run @@ Cluster_client.IDL.T.get result with
       | Ok () ->
-          alert_for_cluster_host_leave ~__context ~cluster_host:self ;
+          Helpers.call_api_functions ~__context (fun rpc session_id ->
+              Client.Client.Cluster.cstack_sync ~rpc ~session_id ~self:cluster
+          ) ;
           Db.Cluster_host.destroy ~__context ~self ;
           debug "Cluster_host.%s was successful" fn_str ;
           Xapi_clustering.Daemon.disable ~__context
       | Error error ->
           warn "Error occurred during Cluster_host.%s" fn_str ;
           if force then (
-            alert_for_cluster_host_leave ~__context ~cluster_host:self ;
+            Helpers.call_api_functions ~__context (fun rpc session_id ->
+                Client.Client.Cluster.cstack_sync ~rpc ~session_id ~self:cluster
+            ) ;
             let ref_str = Ref.string_of self in
             Db.Cluster_host.destroy ~__context ~self ;
             debug "Cluster_host %s force destroyed." ref_str
@@ -330,7 +319,9 @@ let forget ~__context ~self =
           Db.Cluster.set_pending_forget ~__context ~self:cluster ~value:[] ;
           (* must not disable the daemon here, because we declared another unreachable node dead,
            * not the current one *)
-          alert_for_cluster_host_leave ~__context ~cluster_host:self ;
+          Helpers.call_api_functions ~__context (fun rpc session_id ->
+              Client.Client.Cluster.cstack_sync ~rpc ~session_id ~self:cluster
+          ) ;
           Db.Cluster_host.destroy ~__context ~self ;
           debug "Cluster_host.forget was successful"
       | Error error ->
diff --git a/ocaml/xapi/xapi_clustering.ml b/ocaml/xapi/xapi_clustering.ml
index 3e958ece36..7efc722e67 100644
--- a/ocaml/xapi/xapi_clustering.ml
+++ b/ocaml/xapi/xapi_clustering.ml
@@ -438,74 +438,87 @@ module Watcher = struct
     in
     match Idl.IdM.run @@ Cluster_client.IDL.T.get m with
     | Ok diag ->
-        Db.Cluster.set_is_quorate ~__context ~self:cluster
-          ~value:diag.is_quorate ;
-        let all_cluster_hosts = Db.Cluster_host.get_all ~__context in
-        let ip_ch =
-          List.map
-            (fun ch ->
-              let pIF = Db.Cluster_host.get_PIF ~__context ~self:ch in
-              let ipstr =
-                ip_of_pif (pIF, Db.PIF.get_record ~__context ~self:pIF)
-                |> ipstr_of_address
-              in
-              (ipstr, ch)
-            )
-            all_cluster_hosts
-        in
-        let current_time = API.Date.now () in
-        ( match diag.quorum_members with
-        | None ->
-            List.iter
-              (fun self ->
-                Db.Cluster_host.set_live ~__context ~self ~value:false ;
-                Db.Cluster_host.set_last_update_live ~__context ~self
-                  ~value:current_time
+        ( Db.Cluster.set_is_quorate ~__context ~self:cluster
+            ~value:diag.is_quorate ;
+          let all_cluster_hosts = Db.Cluster_host.get_all ~__context in
+          let live_hosts =
+            Db.Cluster_host.get_refs_where ~__context
+              ~expr:(Eq (Field "live", Literal "true"))
+          in
+          let dead_hosts =
+            List.filter (fun h -> not (List.mem h live_hosts)) all_cluster_hosts
+          in
+          let ip_ch =
+            List.map
+              (fun ch ->
+                let pIF = Db.Cluster_host.get_PIF ~__context ~self:ch in
+                let ipstr =
+                  ip_of_pif (pIF, Db.PIF.get_record ~__context ~self:pIF)
+                  |> ipstr_of_address
+                in
+                (ipstr, ch)
               )
               all_cluster_hosts
-        | Some nodel ->
-            let quorum_hosts =
-              List.filter_map
-                (fun {addr; _} ->
-                  let ipstr = ipstr_of_address addr in
-                  match List.assoc_opt ipstr ip_ch with
-                  | None ->
-                      error
-                        "%s: cannot find cluster host with network address %s, \
-                         ignoring this host"
-                        __FUNCTION__ ipstr ;
-                      None
-                  | Some ch ->
-                      Some ch
+          in
+          let current_time = API.Date.now () in
+          match diag.quorum_members with
+          | None ->
+              List.iter
+                (fun self ->
+                  Db.Cluster_host.set_live ~__context ~self ~value:false ;
+                  Db.Cluster_host.set_last_update_live ~__context ~self
+                    ~value:current_time
                 )
-                nodel
-            in
-            let missing_hosts =
+                all_cluster_hosts
+          | Some nodel ->
+              (* nodel contains the current members of the cluster, according to corosync *)
+              let quorum_hosts =
+                List.filter_map
+                  (fun {addr; _} ->
+                    let ipstr = ipstr_of_address addr in
+                    match List.assoc_opt ipstr ip_ch with
+                    | None ->
+                        error
+                          "%s: cannot find cluster host with network address \
+                           %s, ignoring this host"
+                          __FUNCTION__ ipstr ;
+                        None
+                    | Some ch ->
+                        Some ch
+                  )
+                  nodel
+              in
+
+              (* hosts_left contains the hosts that were live, but not in the list
+                 of live hosts according to the cluster stack *)
+              let hosts_left =
+                List.filter (fun h -> not (List.mem h quorum_hosts)) live_hosts
+              in
+              (* hosts_joined contains the hosts that were dead but exists in the db,
+                 and is now viewed as a member of the cluster by the cluster stack *)
+              let hosts_joined =
+                List.filter (fun h -> List.mem h quorum_hosts) dead_hosts
+              in
+              debug "%s: there are %d hosts joined and %d hosts left"
+                __FUNCTION__ (List.length hosts_joined) (List.length hosts_left) ;
+
+              List.iter
+                (fun self ->
+                  Db.Cluster_host.set_live ~__context ~self ~value:true ;
+                  Db.Cluster_host.set_last_update_live ~__context ~self
+                    ~value:current_time
+                )
+                quorum_hosts ;
               List.filter
                 (fun h -> not (List.mem h quorum_hosts))
                 all_cluster_hosts
-            in
-            let new_hosts =
-              List.filter
-                (fun h -> not (Db.Cluster_host.get_live ~__context ~self:h))
-                quorum_hosts
-            in
-            List.iter
-              (fun self ->
-                Db.Cluster_host.set_live ~__context ~self ~value:true ;
-                Db.Cluster_host.set_last_update_live ~__context ~self
-                  ~value:current_time
-              )
-              new_hosts ;
-            List.iter
-              (fun self ->
-                Db.Cluster_host.set_live ~__context ~self ~value:false ;
-                Db.Cluster_host.set_last_update_live ~__context ~self
-                  ~value:current_time
-              )
-              missing_hosts ;
-            maybe_generate_alert ~__context ~missing_hosts ~new_hosts
-              ~num_hosts:(List.length quorum_hosts) ~quorum:diag.quorum
+              |> List.iter (fun self ->
+                     Db.Cluster_host.set_live ~__context ~self ~value:false ;
+                     Db.Cluster_host.set_last_update_live ~__context ~self
+                       ~value:current_time
+                 ) ;
+              maybe_generate_alert ~__context ~hosts_left ~hosts_joined
+                ~num_hosts:(List.length quorum_hosts) ~quorum:diag.quorum
         ) ;
         Db.Cluster.set_quorum ~__context ~self:cluster
           ~value:(Int64.of_int diag.quorum) ;
@@ -527,6 +540,10 @@ module Watcher = struct
      is an update *)
   let cluster_change_interval = 60.
 
+  (* we handle unclean hosts join and leave in the watcher, i.e. hosts joining and leaving
+     due to network problems, power cut, etc. Join and leave initiated by the
+     API will be handled in the API call themselves, but they share the same code
+     as the watcher. *)
   let watch_cluster_change ~__context ~host =
     while !Daemon.enabled do
       let m =