ITIA Logs

The write volume is huge, and reading a metric over a time range means pulling it out of a table row by row, which gets slow as history grows. Writing: 4000 systems with 200 values each, polled every 15 seconds, is 800,000 values per poll round, more than 3 million rows a minute,...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026

For sources Prometheus can't scrape directly, such as network gear reachable only via SNMP or short-lived batch jobs. They push their metrics to the gateway, and Prometheus scrapes the gateway like any other exporter. * Pushers on one side, a normal scrape on the other. * Pull o...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026

By sharding: several independent Prometheus instances each scrape a different part of the estate. For high availability, let two instances scrape the same part, so the data exists twice independently. * Shards for scale, a second scraper per shard for HA, one place to administer...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026

/metrics is the HTTP page Prometheus scrapes. It lists every metric as plain text: a name, optional labels in braces and the current value, with # HELP and # TYPE lines describing it. * Name, labels, value, type: the four parts of every metric. * An excerpt from a Node Exporter:...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026

Its root structure is a timeline rather than tables of rows: every value is attached to a point in time, so "give me metric X from t1 to t2" is the native query and needs no transposing. In a relational database, a time range has to be assembled: find the rows, sort them by times...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026

Prometheus decides. Alert rules are defined and evaluated in Prometheus, which sends firing alerts to the Alertmanager. The Alertmanager only handles delivery: grouping, silencing, routing and paging. * Prometheus decides, the Alertmanager delivers. * The split of duties: Pro...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026

Prometheus keeps recent data and writes selected metrics to a second TSDB built for long-term storage, such as InfluxDB or Graphite. Downsampling means averaging data into coarser intervals before storing it long term. * Same trend, 240 times less data: hourly averages instead o...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026

A counter only goes up (it resets to 0 on restart), like total bytes received. A gauge can go up and down, like current RAM in use. You almost always wrap a counter in rate(); a gauge you read directly. * A counter only climbs (until a restart resets it); a gauge moves both ways...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026

The current state of a service is just a time series with a single (latest) element. Add a rule engine that fires when values cross a threshold and monitoring falls out as a by-product of collecting trending data. * One collection run, two uses: range queries for trending, lates...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026

It fires when a scrape target has been unreachable for more than five minutes. An "instance" is one exporter endpoint, not a whole machine. * for: 5m in action: pending first, firing only after five minutes of up == 0. * up is a metric Prometheus creates itself for every target...

Quiz: ITIA / Monitoring Lab: Prometheus and Grafana | updated: Oct 01, 2026