There's also a ticket open about it[1].
[0] https://prometheus.io/docs/introduction/roadmap/#backfill-ti...
https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/FAQ
(Not affiliated, just impressed with the author's blog posts explaining how it's better than competitors.)
Not sure why restoring data after a crash isn't a bigger problem in your eyes, though. In the context of fully understanding system stability through prometheus, that's a pretty giant gap in your post portem analysis without any way to correct it. It forces you into either using two tools to be able to do that sort of analysis, or accepting that you're always going to risk losing valuable data.
Re: restoration, we use facilities like EBS snapshots, so its separated from prometheus. It could theoretically be an issue for post mortem analysis but data loss is relatively rare so in practice the ability to run post mortems has never been affected. Generally we don't consider our metrics as "business-critical" as production data (e.g. we wouldn't consider the above acceptable for MySQL) so that's where the leniency comes in. I can see different orgs weighing this differently -- we're not really an "infrastructure" company so I think the tradeoff is right for us, but if I was at a PaaS or IaaS I would feel differently.
"Get up to speed with Prometheus, the metrics-based monitoring system used by tens of thousands of organizations in production. This practical guide provides application developers, sysadmins, and DevOps practitioners with a hands-on introduction to the most important aspects of Prometheus, including dashboarding and alerting, direct code instrumentation, and metric collection from third-party systems with exporters."
Also, accurate reporting and backfill are not related.
Curious to know why you don't think accurate reporting and backfilling aren't related. In my experience, they absolutely are -- mostly during disaster scenarios, where that information is more critical than any other time.
I strongly disagree. If you are unable to backfill data then report accuracy will be affected during multiple scenarios, including migrations from other products, unplanned downtime etc. Not having backfill is accepting that reports will suffer as soon as historical data is inaccurate and basically saying that you don't care.