You can make a difference in the Apple Support Community!

When you sign up with your Apple Account, you can provide valuable feedback to other community members by upvoting helpful replies and User Tips.

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

external ssd as boot and data disk iMac 2015 Big Sur

I have an iMac mid 2015. It has a regular hard drive 7200rpm. I have an external TimeMachine 3TB HD.

I bought an external SSD drive, 1tb sandisk usb 3.0. I was able to reformat the SSD and place macOS Big Sur on it. I have it as my boot drive but I am not able to copy over the data to the external SSD using the migration assistant tool. When I tried using the tool and TM as the source I am not able to choose the destination. it starts and it seems that the destination is the internal hard drive. As it list this mac. I want to use external SSD us both a boot disk and data drive. I’m connecting through USB 3.0.

iMac Line (2012 and Later)

Posted on Jan 21, 2023 12:43 PM

Reply
Question marked as Top-ranking reply

Posted on Jan 21, 2023 1:51 PM

What system is on your internal drive? If it's Big Sur then do the following;


1 - erase the external SSD and format it APFS with GUID partition with Disk Utility

2 - download and run Carbon Copy Cloner .

3 - drag the internal drive into the left hand box and the SSD into the middle box.

4 - Control (right) - click on the SSD in the middle box and select "Legacy Backup Assistant…" from the contextual menu.



5 - click on Start and let CCC do it's thing.


When done change the Startup disk in System Settings to the SSD and reboot and run for a while to make sure all is well. Once you're sure the SSD is working as it should you can erase the internal drive and use it for storage.




Similar questions

7 replies
Question marked as Top-ranking reply

Jan 21, 2023 1:51 PM in response to 27-imac-mid_2015

What system is on your internal drive? If it's Big Sur then do the following;


1 - erase the external SSD and format it APFS with GUID partition with Disk Utility

2 - download and run Carbon Copy Cloner .

3 - drag the internal drive into the left hand box and the SSD into the middle box.

4 - Control (right) - click on the SSD in the middle box and select "Legacy Backup Assistant…" from the contextual menu.



5 - click on Start and let CCC do it's thing.


When done change the Startup disk in System Settings to the SSD and reboot and run for a while to make sure all is well. Once you're sure the SSD is working as it should you can erase the internal drive and use it for storage.




Jan 24, 2023 8:39 AM in response to 27-imac-mid_2015

I tried the CCC (ver 6) twice. When I look at disk utility, it shows the SSD with two parts / volumes under the main SSD drive name (it end in media). One is HD and the other HD – Data.

But it doesn’t show as a boot disk in disk startup.

it looks like CCC copied everything from the internal try to the external SSD, but its not showing as a boot disk.

I read somewhere problems with Catalina and maybe reading CCC copies.

Big Sur is the latest OS for my mid 2015 iMac.

Not sure what else to try.

Jan 24, 2023 11:47 AM in response to Old Toad

I tried that, as it was mentioned, but I only see the internal HD.


taking a step back of how I got here.


What I was trying to do is have an external SSD as a boot and data on the same external SSD. I wanted to avoid using the internal hard drive still connected to the inside of my iMac because the speed on my computer is so slow.

but am I thinking about this correctly?


Maybe I only need to make the external SSD drive a boot or a data instead of both?


The goal in purchasing the external SSD drive was to speed up my computer. quite often It is quite slow when doing just normal tasks. Internet browser use; grading multiple assignments with open tabs on multiple web browsers. No video editing involved here.

external ssd as boot and data disk iMac 2015 Big Sur

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.