docs/Cluster-VictoriaMetrics.md: adjust RAM sizing recommendations for vmstorage nodes

It is recommended to have at least of 50% of free RAM on vmstorage nodes in order handle possible
RAM usage spikes during rolling upgrade for vmstorage nodes when time series
are re-routed from temporarily unavailable node to the remaining active nodes.
This commit is contained in:
Aliaksandr Valialkin 2020-11-18 13:00:32 +02:00
parent a11659013f
commit 7e4bcbd853

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@ -285,7 +285,7 @@ Each instance type - `vminsert`, `vmselect` and `vmstorage` - can run on the mos
#### vmstorage #### vmstorage
* The recommended total number of vCPU cores for all the `vmstorage` instances can be calculated from the ingestion rate: `vCPUs = ingestion_rate / 150K`. * The recommended total number of vCPU cores for all the `vmstorage` instances can be calculated from the ingestion rate: `vCPUs = ingestion_rate / 150K`.
* The recommended total amount of RAM for all the `vmstorage` instances can be calculated from the number of active time series: `RAM = active_time_series * 1KB`. * The recommended total amount of RAM for all the `vmstorage` instances can be calculated from the number of active time series: `RAM = 2 * active_time_series * 1KB`.
Time series is active if it received at least a single data point during the last hour or if it has been queried during the last hour. Time series is active if it received at least a single data point during the last hour or if it has been queried during the last hour.
The required RAM per each `vmstorage` should be multiplied by `-replicationFactor` if [replication](#replication-and-data-safety) is enabled. The required RAM per each `vmstorage` should be multiplied by `-replicationFactor` if [replication](#replication-and-data-safety) is enabled.
Additional RAM can be required for query processing. Additional RAM can be required for query processing.