This is all relative but I don't personally think so. Not on EC2+EBS, anyway. Certainly not as difficult as running/scaling an ES or Kafka cluster.

It's a completely different problem because by default Prometheus does not shard anything so you're bound to a single instance, where ES and Kafka are cluster based.

Out of interest what do you find hard about running ElasticSearch clusters?

In my experience ES has been one of the easiest clustered / highly available and sharded systems I've ever run - especially for how incredibly performant and reliable it is.

I've generally found that beyond right sizing your nodes, indexes and shard configuration - it pretty much just works without ever really having issues.

Victoria Metrics is an absolutely superb drop in replacement.

It's not a drop-in replacement (even though it tries to sell itself as such), it's incompatible in a significant number of ways and throws away part of your data.

We use Victoria Metrics in Prod for more than 6 months. It is very reliable and scalable. Victoria metrics handles more than 2B+ series in our setup without breaking a sweat.

No, it's better. You can focus on the thing you're measuring rather than the bloody platform.

They made some pragmatic optimizations by dropping part of the data where it mostly doesn't matter. Who's actually affected by this? 0.01% of users?