I just cloned Sierra onto my external hard drive from my old MBP which also contains Mt. Lion which I would like to get rid of somehow.

I have plugged the external drive into my new MBP but don't know where to go from here. I am using SuperDuper. Artie, are you here? Anyway, I need step by step instructions on how to add another partition to clone Sierra on my new MBP.

I selected the pie and made three partitions. Did I really need to do that? Could I partition it later if I add a different OS or something?

Also, with the 3 partitions I see now, one says Mac HD and one says 2015 MBP Sierra.
My older MBP has 43.4 GB without external HD used out of 500 gb. I don't know how many GB I should give Sierra and keep the rest for my Mac HD.

Keep it simple. If you know me, you know what you're dealing with.

Before we go any further, Rita, please post these three screenshots of Disk Utility (at Imgur); what you've posted doesn't give us enough info about what you're working with to answer your questions. (After you've uploaded pic #1, use the + [plus] button at the bottom of the page to add #s 2 & 3.)

The top shot should be your new MBP's SSD.

The second one should be your old MBP's HDD. (DU shown with your external plugged in.)

The third one should be your old MBP with with your external's HDD selected.

Here you go after much hair pulling out: https://imgur.com/a/wlgw5

Time for a bit more hair pulling: the middle shot should have Apple SSD selected, and the bottom shot should have WD My Passport selected.

If Imgur is hair-pulling, what would you call FreeImageHosting with its "There's a problem"s and then having to extract the URL you want from the one they give you?

Damn! I lost my post.

You ought to give some thought to a few things:

• You've mentioned Time Machine. Do you want to use it? For which MBP or for both?
• Do you want to perpetuate any legacy versions of OS X? Mavericks? Any other?
• Do you want to maintain current clones of one or both MBPs, or do you just want not necessarily up to date external bootable volumes in case of emergency?
• What do you need in the way of non-bootable storage space?

More: You're in an area now that once it's done, it's difficult (at best) to undo if it can be undone at all, so it's best to start with a well thought out plan in place.

I followed your directions as far as the order of the screen shots. I'm not sure why they didn't show up in that order. I put the screen shots in the order you stated and uploaded them in that order. Now I see they are not in that order. Yes, more hair pulling. But you can tell which is which, right?

Nope, I don't like Time Machine.

I will just use Sierra. So, I need to erase Mt. Lion and Mavericks some how. Unless you think I should keep them because they aren't really taking up space and I can't undo that. I could delete Mt. Lion but keep Mavericks, I guess.

I want bootable drives for both MBPs in case of emergency. I've got my old one backed up now with Sierra along with the other two OS's. I just need to back up my new one. That's why I asked how much space I need to give Sierra and the SSD respectively. I have so much less space on the SSD.

(No need for any more screenshots; I've got it figured out...I think.)

I'm not entirely up on changing partition sizes. I know you can do it with no data loss in some instances, and that it's data-destructive in others, but I can't cite the exact circumstances for either. The one thing I know for sure is that (even though nothing's guaranteed) it's best to approach partitioning with a view towards covering the present while anticipating the future.

From looking at your screenshots, I'm guessing that your external is divided into three 333 GB partitions, and I'm sure that that format won't be easily adaptable if the need arises, so I'd change it right now, while it'll be an easy job.

My suggestions... FIRST, MAKE SURE THAT EVERY BIT OF IMPORTANT DATA HAS BEEN SAVED FROM THE DRIVE TO ANOTHER LOCATION!

Then, erase the entire drive: Mt. Lion is unnecessary at this point, and you've complained about your Mavericks installation being wonky from day one, so it won't be any loss either. (If you want to keep Mavericks around, you can do a fresh d/l from the App Store.)

Then, repartition the drive to a format that provides you with logically sized partitions to which to back up both MBPs, restore Mavericks if you want to, back up future macOS upgrades, and save significant amounts of data should the need arise without having to worry about possible data-destructive partition size changes.

And if you want to take the easy way out, simply erase the Mt. Lion partition in Disk Utility, and clone Sierra from your new MBP to the empty partition.

PMFJI but I want to point out...

• Macintosh HD is your boot volume and is 120 GB in size out of which you are curretnluy using only a little over 13 GB
• Allowing for some overhead a clone partition/volume of 150 GB would be more than adequate
• Your Sierra partition/volume on the WD My Passport at 333 GB is twice what you should need for a backup clone
• Artie is correct that changing partition sizes is possible, but there are rules on which partitions can be resized non-destructively, and even if you follow all the rules correctly there is still a finite risk of losing data.

Since you no longer want Mountain Lion and rather than over-complicating the process and your d=current partitions are more than adequate for clone images why not…

1. Erase the Mountain Lion volume
2. Rename it something like Archives or Installers
3. Use the renamed partition to store dowloaded application and OS install .dmg file.

If you were operating much closer to capacity on the partitions then more thought and planning would definitely be in order, but in this case it does not appear to be worth the additional effort.

Here it is anyway.. I only save things to my drive, so where would another location be? Besides, I'm not too worried about it. I'll just keep Sierra on my drive and my old MBP. As you say, I can always d/l Mavericks again should I want to. And, yeah, I think I'll take the easy way out.

I like it when you jump in. No worries.

I think I've been asking the wrong questions. I don't really need to partition my Internal SSD. I've never done that before with my old HDD and don't feel the need to now. I'm making this more complicated than I need to. After doing this for a few days, I think I just want to put Sierra onto my external drive and back it up occasionally like I am doing with my HDD. It's just been so many years since I partitioned my ext. drive that I forgot what to do.

I just now resized my external drive partitions and erased Mt. Lion. Unfortunately, it still shows up and the numbers I resized everything to changed to another number. I'd just better leave this alone I guess and backup Sierra on my new MBP. My external drive will no longer allow me to resize the partitions, maybe that is what you and Artie were warning me about. Fortunately, they are large enough to hold what I need.