[jrv]

Yeah, as Prometheus's local storage is meant more as a transient / non-durable metrics store, the only current way to migrate while simultaneously accessing old and new data is to run both the old and new servers and have the new one read old data from the other one via the remote-read integration.

Someone could write a tool to do a full migration of the old storage format to the new one, but the formats are completely different and at least in the naive version of such tooling, that would have to happen offline and take a very long time to run for large storages.

EDIT: If you would like to fund development of such a tool, let us know :)

[sz4kerto]

> EDIT: If you would like to fund development of such a tool, let us know :)

We're too small for that, unfortunately. Someone said at DockerCon that migrating large (multi-TB) stores would take a long time; this doesn't apply to us, we have only ~0.1 TB perf data as of now.

[jrv]

Out of curiosity, do you care about migrating the data online, or would a brief Prometheus downtime (and thus gap in data) be ok?

[sz4kerto]

Downtime would be acceptable I think, especially because we could just launch a separate instance of Prom while the main one is being migrated.