I am trying to clone a 2TB drive that has mac os x 10.6.8 onto a smaller drive but dont know what I am doing I have a Mac Pro that I cant install an OS onto at the moment because I do not have snow leopard. I do have a bootable 2TB Western Digital drive that comes from an identical Mac Pro that has 10.6.8 loaded onto it. I have tested this drive onto the computer in question and it boots ok. I only have a 250 GB drive to use as a target disk. The 2TB drive has only about 65GB used space. When I try to shrink the partition via Gparted, a caution exclamation point w an orange box appears that says it can not read the contents of this drive while terminal indicates that gparted only supports 512 byte length sectors and the journaled drive is not 512 byte length. When I mount the drive, the exclamation point goes away but mounting it doesnt allow me to shrink the partition. 


link to my previous related question: Mac Pro install disk keeps ejecting itself
Assuming your info is correct &amp; there is going to be room on the 250, this should be simple in a Pro.


Put both drives in the Mac Pro.
Boot from the one that works.
Format the other [just to be certain] in Disk Utility as a single volume, GUID/HFS+ [Don't name it exactly as the other, to save confusion]
Get Carbon Copy Cloner*. Paid, but demo available - It's worth owning.
Clone one to the other.
Remove the old drive. 
Boot to the new drive.
Change its name to that of the old drive
This will just fix anything that is using the actual volume name - it shouldn't, but it might be. You can skip this step &amp; see if anything falls over, if you want to separate the names long-term.
Done.


* Looks like you will need an older version - 3.5.7 from the bottom of this page - https://bombich.com/download