         host       : undefined  # defaults to current host, if deployed
         unset_loc  : false      # set location to undefined in the database
         umount     : false      # don't use this -- it causes ZFS deadlock, which requires machine reboots.  Horrible and not needed.
+        wait_for_replicate : false  # if true, waits for post-snapshot replication to complete
         cb         : required
 
     if not opts.host?

                        if err
                            cb(err)
                        else
                            snapshot = output.stdout.trim()
                            cb()
        (cb) ->
            dbg("rollback to #{snapshot}")
            execute_on
                host    : opts.host
                command : "sudo zfs rollback #{snapshot}"
                timeout : 300
                cb      : cb
    ], (err) -> opts.cb?(err))

        cb         : undefined

    dbg = (m) -> winston.debug("rollback_to_snapshot(#{opts.project_id},#{opts.host},#{opts.snapshot}): #{m}")
    snapshot_name = opts.snapshot
    f = filesystem(opts.project_id)

    async.series([
        (cb) ->
            if snapshot_name?
                if snapshot_name.indexOf('@') == -1
                    snapshot_name = opts.project_id + "@" + snapshot_name
                cb()
            else
                dbg("get most recent snapshot name")
