docs/troubleshooting: mention issue with un-ordered labels

See https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5219#issuecomment-1773441711

Signed-off-by: hagen1778 <roman@victoriametrics.com>
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hagen1778 2023-10-30 13:53:14 +01:00
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@ -415,6 +415,14 @@ The most common sources of cluster instability are:
see [replication and data safety docs](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#replication-and-data-safety)
for details.
- Time series sharding. Received time series [are consistently sharded](https://docs.victoriametrics.com/vmalert.html#rules-backfilling)
by `vminsert` between configured `vmstorage` nodes. As a sharding key `vminsert` is using time series name and labels,
respecting their order. If the order of labels in time series is constantly changing, this could cause wrong sharding
calculation and result in un-even and sub-optimal time series distribution across available vmstorages. It is expected
that metrics pushing client is responsible for consistent labels order (like `Prometheus` or `vmagent` during scraping).
If this can't be guaranteed, set `-sortLabels=true` cmd-line flag to `vminsert`. Please note, sorting may increase
CPU usage for `vminsert`.
The obvious solution against VictoriaMetrics cluster instability is to make sure cluster components
have enough free resources for graceful processing of the increased workload.
See [capacity planning docs](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#capacity-planning)