Hi! I'm running Ubuntu 12.04 on an old hard drive and migrating to Ubuntu 14.04 on a new SSD. I previously installed and used thunderbird 38.4.0 and lightning 4.0.4 on the HD drive. I have installed the same versions of thunderbird and lightning on the SSD, created a new profile with the same account information. Within that profile there is a new name for the .default directory. Still on the SSD changed the name of new profile, then linked the original name of the new profile to the profile on the hard drive. Within that installation, I created a link with the name of the new .default directory on the SSD to the existing .default directory on the HD. After booting to Ubuntu 14.04, mail works fine but lightning starts with a warning that the version of lightning must be 4.0 or later. But it is as is the version on the 12.04 system. In the same session when I try to look at the calendar, the system crashes.

So the basic question is how to use one drive for the OS and local apps, and another drive for the data (.i.e., mailbox and calendar in this case). If this configuration works, I can maintain new OS's and applications on one drive and maintain data on another drive.