read-only git repositories

given that git already treats everything in the object storage as being fixed it occured to me that there may be value in makeing it so that git can make use of more then one pool of storage.

possible uses of this would be to have a bunch of data on read-only media (say the 3G+ kernel history on a DVD), having a pruned local object store with automated fetching from elsewhere if the object isn't found locally, or marking the object store that you plan on sharing with the world as read-only (with your changed object going into a secondary store) so that you don't pollute it accidently (this could also cut down on the storage requirements)

there are probably other uses and it seems like a fairly small modification to add a hook to use if the object isn't found initially that I thought I'd mention it to the group.

David Lang