docs: sync with cluster branch

docs/CHANGELOG.md

@@ -6,6 +6,8 @@ sort: 15
 
 ## tip
 
+* FEATURE: [VictoriaMetrics cluster](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html): add `-dropSamplesOnOverload` command-line flag for `vminsert`. If this flag is set, then `vminsert` drops incoming data if the destination `vmstorage` is temporarily unavailable or cannot keep up with the ingestion rate. The number of dropped rows can be [monitored](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#monitoring) via `vm_rpc_rows_dropped_on_overload_total` metric at `vminsert`.
+* FEATURE: [VictoriaMetrics cluster](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html): improve re-routing logic, so it re-routes incoming data more evenly if some of `vmstorage` nodes are temporarily unavailable and/or accept data at slower rate than other `vmstorage` nodes.
 * FEATURE: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): cover more cases with the [label filters' propagation optimization](https://utcc.utoronto.ca/~cks/space/blog/sysadmin/PrometheusLabelNonOptimization). This should improve the average performance for practical queries. The following cases are additionally covered:
   * Multi-level [transform functions](https://docs.victoriametrics.com/MetricsQL.html#transform-functions). For example, `abs(round(foo{a="b"})) + bar{x="y"}` is now optimized to `abs(round(foo{a="b",x="y"})) + bar{a="b",x="y"}`
   * Binary operations with `on()`, `without()`, `group_left()` and `group_right()` modifiers. For example, `foo{a="b"} on (a) + bar` is now optimized to `foo{a="b"} on (a) + bar{a="b"}`

docs/Cluster-VictoriaMetrics.md

@@ -483,7 +483,9 @@ Below is the output for `/path/to/vminsert -help`:
     	The maximum size in bytes of a single DataDog POST request to /api/v1/series
     	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 67108864)
   -disableRerouting
-    	Whether to disable re-routing when some of vmstorage nodes accept incoming data at slower speed compared to other storage nodes. Disabled re-routing limits the ingestion rate by the slowest vmstorage node. On the other side, disabled re-routing minimizes the number of active time series in the cluster during rolling restarts and during spikes in series churn rate (default true)
+    	Whether to disable re-routing when some of vmstorage nodes accept incoming data at slower speed compared to other storage nodes. Disabled re-routing limits the ingestion rate by the slowest vmstorage node. On the other side, disabled re-routing minimizes the number of active time series in the cluster during rolling restarts and during spikes in series churn rate. See also -dropSamplesOnOverload (default true)
+  -dropSamplesOnOverload
+    	Whether to drop incoming samples if the destination vmstorage node is overloaded and/or unavailable. This prioritizes cluster availability over consistency, e.g. the cluster continues accepting all the ingested samples, but some of them may be dropped if vmstorage nodes are temporarily unavailable and/or overloaded
   -enableTCP6
     	Whether to enable IPv6 for listening and dialing. By default only IPv4 TCP and UDP is used
   -envflag.enable