Is it possible to mount a filesystem via sshfs on my mac and have time machine back that up to external disk?
Time machine does backup any other external drives to its dedicated external drive so this problem reduces to having TM recognize the sshfs volume. How do I do this?
You can mount SSHFS with MacFUSE.
In order to back it up, it's a little tricky but there were other people with the same problem (most related to NFS); I've read that Time machine needs the support to hard links, so the solution is to use a compatible format: you have to create (check hdiutil's man page) a sparse disk image or a sparsebundle (check tmutil if you have OS X 10.7+).
