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docs: make more clear the relation between replication and deduplication

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This is based on https://github.com/VictoriaMetrics/VictoriaMetrics/pull/2852
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Aliaksandr Valialkin 2022-07-11 19:15:14 +03:00
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4
README.md
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@ -1255,7 +1255,7 @@ with the enabled de-duplication. See [this section](#deduplication) for details.
VictoriaMetrics leaves a single raw sample with the biggest timestamp per each `-dedup.minScrapeInterval` discrete interval if `-dedup.minScrapeInterval` is set to positive duration. For example, `-dedup.minScrapeInterval=60s` would leave a single raw sample with the biggest timestamp per each discrete 60s interval. If multiple raw samples have the same biggest timestamp on the given `-dedup.minScrapeInterval` discrete interval, then an arbitrary sample out of these samples is left. This aligns with the [staleness rules in Prometheus](https://prometheus.io/docs/prometheus/latest/querying/basics/#staleness).
The `-dedup.minScrapeInterval=D` is equivalent to `-downsampling.period=0s:D` if [downsampling](#downsampling) is enabled. It is safe to use deduplication and downsampling simultaneously.
The `-dedup.minScrapeInterval=D` is equivalent to `-downsampling.period=0s:D` if [downsampling](#downsampling) is enabled. So it is safe to use deduplication and downsampling simultaneously.
The recommended value for `-dedup.minScrapeInterval` must equal to `scrape_interval` config from Prometheus configs. It is recommended to have a single `scrape_interval` across all the scrape targets. See [this article](https://www.robustperception.io/keep-it-simple-scrape_interval-id) for details.
@ -1263,6 +1263,8 @@ The de-duplication reduces disk space usage if multiple identically configured [
write data to the same VictoriaMetrics instance. These vmagent or Prometheus instances must have identical
`external_labels` section in their configs, so they write data to the same time series. See also [how to set up multiple vmagent instances for scraping the same targets](https://docs.victoriametrics.com/vmagent.html#scraping-big-number-of-targets).
It is recommended passing different `-promscrape.cluster.name` values to HA paris of `vmagent` instances, so the de-duplication consistently leaves samples for one `vmagent` instance and removes duplicate samples from other `vmagent` instances. See [these docs](https://docs.victoriametrics.com/vmagent.html#high-availability) for details.
## Storage
VictoriaMetrics stores time series data in [MergeTree](https://en.wikipedia.org/wiki/Log-structured_merge-tree)-like

10
app/vmagent/README.md
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@ -509,7 +509,15 @@ If each target is scraped by multiple `vmagent` instances, then data deduplicati
The `-dedup.minScrapeInterval` must be set to the `scrape_interval` configured at `-promscrape.config`.
See [these docs](https://docs.victoriametrics.com/#deduplication) for details.
If multiple `vmagent` clusters scrape the same set of targets, then each cluster must have unique value for the `-promscrape.cluster.name` command-line flag.
## High availability
It is possible to run multiple identically configured `vmagent` instances or `vmagent` [clusters](#scraping-big-number-of-targets),
so they [scrape](#how-to-collect-metrics-in-prometheus-format) the same set of targets and push the collected data to the same set of VictoriaMetrics remote storage systems.
In this case the deduplication must be configured at VictoriaMetrics in order to de-duplicate samples received from multiple identically configured `vmagent` instances or clusters.
See [these docs](https://docs.victoriametrics.com/#deduplication) for details.
It is also recommended passing different values to `-promscrape.cluster.name` command-line flag per each `vmagent` instance or per each `vmagent` cluster in HA setup.
This is needed for proper data de-duplication. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2679) for details.
## Scraping targets via a proxy

2
docs/Cluster-VictoriaMetrics.md
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@ -406,7 +406,7 @@ The replication can be enabled by passing `-replicationFactor=N` command-line fl
The cluster must contain at least `2*N-1` `vmstorage` nodes, where `N` is replication factor, in order to maintain the given replication factor for newly ingested data when `N-1` of storage nodes are unavailable.
When the replication is enabled, `-dedup.minScrapeInterval=1ms` command-line flag must be passed to `vmselect` nodes, so they could de-duplicate replicated samples obtained from distinct `vmstorage` nodes during querying. If duplicate data is pushed to VictoriaMetrics from identically configured [vmagent](https://docs.victoriametrics.com/vmagent.html) instances or Prometheus instances, then the `-dedup.minScrapeInterval` must be set to bigger values according to [deduplication docs](#deduplication).
VictoriaMetrics stores timestamps with millisecond precision, so `-dedup.minScrapeInterval=1ms` command-line flag must be passed to `vmselect` nodes when the replication is enabled, so they could de-duplicate replicated samples obtained from distinct `vmstorage` nodes during querying. If duplicate data is pushed to VictoriaMetrics from identically configured [vmagent](https://docs.victoriametrics.com/vmagent.html) instances or Prometheus instances, then the `-dedup.minScrapeInterval` must be set to `scrape_interval` from scrape configs according to [deduplication docs](#deduplication).
Note that [replication doesn't save from disaster](https://medium.com/@valyala/speeding-up-backups-for-big-time-series-databases-533c1a927883), so it is recommended performing regular backups. See [these docs](#backups) for details.

4
docs/README.md
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@ -1255,7 +1255,7 @@ with the enabled de-duplication. See [this section](#deduplication) for details.
VictoriaMetrics leaves a single raw sample with the biggest timestamp per each `-dedup.minScrapeInterval` discrete interval if `-dedup.minScrapeInterval` is set to positive duration. For example, `-dedup.minScrapeInterval=60s` would leave a single raw sample with the biggest timestamp per each discrete 60s interval. If multiple raw samples have the same biggest timestamp on the given `-dedup.minScrapeInterval` discrete interval, then an arbitrary sample out of these samples is left. This aligns with the [staleness rules in Prometheus](https://prometheus.io/docs/prometheus/latest/querying/basics/#staleness).
The `-dedup.minScrapeInterval=D` is equivalent to `-downsampling.period=0s:D` if [downsampling](#downsampling) is enabled. It is safe to use deduplication and downsampling simultaneously.
The `-dedup.minScrapeInterval=D` is equivalent to `-downsampling.period=0s:D` if [downsampling](#downsampling) is enabled. So it is safe to use deduplication and downsampling simultaneously.
The recommended value for `-dedup.minScrapeInterval` must equal to `scrape_interval` config from Prometheus configs. It is recommended to have a single `scrape_interval` across all the scrape targets. See [this article](https://www.robustperception.io/keep-it-simple-scrape_interval-id) for details.
@ -1263,6 +1263,8 @@ The de-duplication reduces disk space usage if multiple identically configured [
write data to the same VictoriaMetrics instance. These vmagent or Prometheus instances must have identical
`external_labels` section in their configs, so they write data to the same time series. See also [how to set up multiple vmagent instances for scraping the same targets](https://docs.victoriametrics.com/vmagent.html#scraping-big-number-of-targets).
It is recommended passing different `-promscrape.cluster.name` values to HA paris of `vmagent` instances, so the de-duplication consistently leaves samples for one `vmagent` instance and removes duplicate samples from other `vmagent` instances. See [these docs](https://docs.victoriametrics.com/vmagent.html#high-availability) for details.
## Storage
VictoriaMetrics stores time series data in [MergeTree](https://en.wikipedia.org/wiki/Log-structured_merge-tree)-like

4
docs/Single-server-VictoriaMetrics.md
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@ -1259,7 +1259,7 @@ with the enabled de-duplication. See [this section](#deduplication) for details.
VictoriaMetrics leaves a single raw sample with the biggest timestamp per each `-dedup.minScrapeInterval` discrete interval if `-dedup.minScrapeInterval` is set to positive duration. For example, `-dedup.minScrapeInterval=60s` would leave a single raw sample with the biggest timestamp per each discrete 60s interval. If multiple raw samples have the same biggest timestamp on the given `-dedup.minScrapeInterval` discrete interval, then an arbitrary sample out of these samples is left. This aligns with the [staleness rules in Prometheus](https://prometheus.io/docs/prometheus/latest/querying/basics/#staleness).
The `-dedup.minScrapeInterval=D` is equivalent to `-downsampling.period=0s:D` if [downsampling](#downsampling) is enabled. It is safe to use deduplication and downsampling simultaneously.
The `-dedup.minScrapeInterval=D` is equivalent to `-downsampling.period=0s:D` if [downsampling](#downsampling) is enabled. So it is safe to use deduplication and downsampling simultaneously.
The recommended value for `-dedup.minScrapeInterval` must equal to `scrape_interval` config from Prometheus configs. It is recommended to have a single `scrape_interval` across all the scrape targets. See [this article](https://www.robustperception.io/keep-it-simple-scrape_interval-id) for details.
@ -1267,6 +1267,8 @@ The de-duplication reduces disk space usage if multiple identically configured [
write data to the same VictoriaMetrics instance. These vmagent or Prometheus instances must have identical
`external_labels` section in their configs, so they write data to the same time series. See also [how to set up multiple vmagent instances for scraping the same targets](https://docs.victoriametrics.com/vmagent.html#scraping-big-number-of-targets).
It is recommended passing different `-promscrape.cluster.name` values to HA paris of `vmagent` instances, so the de-duplication consistently leaves samples for one `vmagent` instance and removes duplicate samples from other `vmagent` instances. See [these docs](https://docs.victoriametrics.com/vmagent.html#high-availability) for details.
## Storage
VictoriaMetrics stores time series data in [MergeTree](https://en.wikipedia.org/wiki/Log-structured_merge-tree)-like

10
docs/vmagent.md
View file

@ -513,7 +513,15 @@ If each target is scraped by multiple `vmagent` instances, then data deduplicati
The `-dedup.minScrapeInterval` must be set to the `scrape_interval` configured at `-promscrape.config`.
See [these docs](https://docs.victoriametrics.com/#deduplication) for details.
If multiple `vmagent` clusters scrape the same set of targets, then each cluster must have unique value for the `-promscrape.cluster.name` command-line flag.
## High availability
It is possible to run multiple identically configured `vmagent` instances or `vmagent` [clusters](#scraping-big-number-of-targets),
so they [scrape](#how-to-collect-metrics-in-prometheus-format) the same set of targets and push the collected data to the same set of VictoriaMetrics remote storage systems.
In this case the deduplication must be configured at VictoriaMetrics in order to de-duplicate samples received from multiple identically configured `vmagent` instances or clusters.
See [these docs](https://docs.victoriametrics.com/#deduplication) for details.
It is also recommended passing different values to `-promscrape.cluster.name` command-line flag per each `vmagent` instance or per each `vmagent` cluster in HA setup.
This is needed for proper data de-duplication. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2679) for details.
## Scraping targets via a proxy