Authorities should keep recent consensuses, votes, and bandwidth files

Moving https://trac.torproject.org/projects/tor/ticket/21378#comment:12 into a separate ticket:

Quoting teor:

Replying to teor:

Replying to irl:

Using the fixed URL ​http:///tor/status-vote/next/bandwidth.z sounds like it would be very easy to add this to CollecTor.

Thanks for the feedback!

We have discussed in the Metrics team extending dir-spec.txt to allow to fetch "recent" files as well as just next/current. In the case that there is a wide CollecTor outage, and we miss a file, it would be good to have those files cached (on a best-effort basis, not necessarily persisted to disk) and available via some URL.

How is this any different to losing descriptors or consensuses? (Please answer this question on a separate ticket.)

I don't know if karsten already had some ideas about what these URLs would look like, but we should perhaps consider this before implementing changes to dir-spec.txt.

Please open a separate ticket for this feature. It's potentially a large feature. And it's not essential for the initial release of this feature.

If you open a separate ticket for historical directory documents, please make legacy/trac#26698 (moved) a child of that ticket. We'll need bandwidth file hashes to work out the exact file used in each vote.