thoughts

doc/design/assistant/syncing.mdwn

@@ -1,6 +1,27 @@
 Once files are added (or removed or moved), need to send those changes to
 all the other git clones, at both the git level and the key/value level.
 
+## efficiency
+
+Currently after each file transfer (upload or download), a git sync is done
+to all remotes. This is rather a lot of work, also it prevents collecting
+presence changes to the git-annex branch into larger commits, which would
+save disk space over time.
+
+In many cases, this sync is necessary. For example, when a file is uploaded
+to a transfer remote, the location change needs to be synced out so that
+other clients know to grab it.
+
+Or, when downloading a file from a drive, the sync lets other locally
+paired repositories know we got it, so they can download it from us. 
+OTOH, this is also a case where a sync is sometimes unnecessary, since
+if we're going to upload the file to them after getting it, the sync
+only perhaps lets them start downloading it before our transfer queue
+reaches a point where we'd upload it.
+
+Do we need all the mapping stuff discussed below to know when we can avoid
+syncs?
+
 ## TODO
 
 * Test MountWatcher on LXDE.