Per our brief discussion ATM git-annex allows to prioritize URLs only by assigning them to be handled by different special remotes and having different costs for those different remotes.

This doesn't allow for e.g. prioritization within built-in special "web" remote which is the most frequent use case. Our use case:


```
(base) dandi@drogon:/mnt/backup/dandi/dandizarrs/ea8c43c7-757e-4653-8e4a-a6d356120836$ git annex whereis 0/0/0/3/6/169
(recording state in git...)
whereis 0/0/0/3/6/169 (2 copies)
        00000000-0000-0000-0000-000000000001 -- web
        86da9d10-da54-4371-8d6f-7559c6a236f5 -- dandi@drogon:/mnt/backup/dandi/dandizarrs/ea8c43c7-757e-4653-8e4a-a6d356120836 [here]

  web: https://api.dandiarchive.org/api/zarr/ea8c43c7-757e-4653-8e4a-a6d356120836.zarr/0/0/0/3/6/169
  web: https://dandiarchive.s3.amazonaws.com/zarr/ea8c43c7-757e-4653-8e4a-a6d356120836/0/0/0/3/6/169?versionId=h3qb0rOswsssHxEdfN8QAWUMoVhddQrY
ok

```

where we have API-server based URL -- we do not want to access unless really really needed (would be the slowest, would bring load to the server etc), and then direct access to public bucket -- fastest (unless some other local remote has it even better).

Joey envisioned potentially being able to assign priorities via e.g.

    git-annex enableremote web url-priority-1=s3.amazonaws.com/ url-prority-2=/api.dandiarchive.org/

but I also wondered if there could just be some way to provide costs (or adjustments to costs) for different URLs so they all become considered while considering costs across remotes?

E.g. may be I have a URL which is fast (s3 bucket), then I have bunch of average regular remotes with decent speed (e.g. dropbox etc), and then URL to some slow archive (API server). Both urls are served by `web` remote, and there would be no way to "order" all data access schemes/remotes in the optimal sequence of costs unless different URLs could have different costs considered along with different remotes.

PS somehow I have some odd memory of seeing some config option to provide git-annex a script which would output cost given a URL... I disliked that approach since it would require me to code the script, and thus didn't use it. Did I dream it up? 

[[!meta author=yoh]]
[[!tag projects/dandi]]

> [[fixed|done]] --[[Joey]]
