Not that proxying is super slow, but it does involve bouncing content through the proxy, and could be made faster. Some ideas:

• A proxy to a local git repository spawns git-annex-shell to communicate with it. It would be more efficient to operate directly on the Remote. Especially when transferring content to/from it. But: When a cluster has several nodes that are local git repositories, and is sending data to all of them, this would need an alternate interface than storeKey, which supports streaming, of chunks of a ByteString.

• Use sendfile() to avoid data copying overhead when receiveBytes is being fed right into sendBytes. Library to use: https://hackage.haskell.org/package/hsyscall-0.4/docs/System-Syscall.html

• Getting a key from a cluster currently picks from amoung the lowest cost nodes at random. This could be smarter, eg prefer to avoid using nodes that are doing other transfers at the same time.

• The cost of a proxied node that is accessed via an intermediate gateway is currently the same as a node accessed via the cluster gateway. So in such a situation, git-annex may make a suboptimal choice of path. To fix this, there needs to be some way to tell how many hops through gateways it takes to get to a node. Currently the only way is to guess based on number of dashes in the node name, which is not satisfying.

  Even counting hops is not very satisfying, one cluster gateway could be much more expensive to traverse than another one.

  If seriously tackling this, it might be worth making enough information available to use spanning tree protocol for routing inside clusters.

(This is a deferred item from the git-annex proxies megatodo.) --Joey