How to get the oldest timestamp? / How old is my oldest metric?

[applejag]

Prometheus exports the metric prometheus_tsdb_lowest_timestamp_seconds which is the timestamp of the oldest metric.

I cannot find an equivalent metric on Mimir. Is there an equivalent metric, or can I get this information a different way?

[pstibrany]

There is no equivalent, and no easy way to get this information. Mimir would need to compute this from blocks and TSDB Head in each ingester. There is no component doing that right now.

With access to the block storage, one could find the oldest block and take minT of that block. This is easily available in bucket-index.json file. This approach would ignore data from ingesters, but assuming that data on the storage is older, that may not be a problem.