On Yosemite(10.10.1) after installing 1.6.1, all works well with ZFS but the behaviour of how OSX handles
.CDR images seems to have changed.
Formerly I would double click on a .cdr and it would mount.
After installing 1.6.1, double clicking on a saved image (extension .CDR) gives error message that it cannot mount this filesystem.
(Note: this worked prior to installing 1.6.1, even after installing 1.5.2, the version that preceeded it).
WORKAROUND:
Go into disk utility. On the left side will be the name of your .CDR (I keep mine on my desktop).
Click on the name and then click on mount.
After a moment it will again tell you that it cannot be mounted.
But a second name of the CDR (the logical volume ?) will appear beneath it on the left right
under the name you formerly clicked on.
Click on that and then click on the "Mount" icon and this time it will work and be mounted
and the icon for the mounted .cdr will appear on your desktop as usual.