add glacier todo page

doc/design/assistant/cloud.mdwn

@@ -13,7 +13,7 @@ More should be added, such as:
 * Box.com (it's free, and current method is hard to set up and a sorta
   shakey; a better method would be to use its API)
 * Dropbox? That would be ironic.. Via its API, presumably.
-* Amazon Glacier
+* [[Amazon Glacier|todo/special_remote_for_amazon_glacier]]
 
 ## limited space
 

doc/todo/special_remote_for_amazon_glacier.mdwn

@@ -0,0 +1,19 @@
+Amazon's new glacier service would be a nice special remote to support for
+long-term archival.
+
+The main difficulty is that glacier is organized into vaults, and accessing
+a file in a vault takes ~4 hours. A naive implementation would make `git
+annex get` wait for 4 hours, which is certianly not reasonable.
+
+One approach I am pondering is to make each glacier vault a separate
+special remote. You could then request git-annex to spin up a remote, and
+come back later, and be able to access the data stored in it (need to check
+if glacier would also allow adding new data to it then). This is
+conceptually similar to using git-annex with offline removable drives,
+except with glacier, you have a controllable robot to get them plugged in. :)
+
+Ideally, git-annex would arrange for glacier to send it a message when the
+vault becomes available, and the user could queue a list of commands to
+run, or files to transfer, at that point.
+
+--[[Joey]]