backing up a file server with many subvolumes

["J. Hart" <jfhart085@gmail.com>]

I have a Btrfs filesystem on a backup server.  This filesystem has a 
directory to hold backups for filesystems from remote machines.  In this 
directory is a subdirectory for each machine.  Under each machine 
subdirectory is one directory for each filesystem (ex /boot, /home, etc) 
on that machine.  In each filesystem subdirectory are incremental 
snapshot subvolumes for that filesystem.  The scheme is something like 
this:

<top>/backup/<machine>/<filesystem>/<many snapshot subvolumes>

I'd like to try to back up (duplicate) the file server filesystem 
containing these snapshot subvolumes for each remote machine.  The 
problem is that I don't think I can use send/receive to do this. "Btrfs 
send" requires "read-only" snapshots, and snapshots are not recursive as 
yet.  I think there are too many subvolumes which change too often to 
make doing this without recursion practical.

Any thoughts would be most appreciated.

J. Hart