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BACKUPS ON TIME MACHINE

I have bought a new 24" iMac and my husband has my old 21.5" iMac, which is only 2 years old and has a back up drive, which is working well, because he migrated all his stuff from an old MacBook Pro onto the 21.5" iMac, which is working fine.


My back up drive is a LaCie 1 TB, from which I migrated all my files yesterday when I set up the new iMac.


All the data has been transferred to my new iMac so my question is can I just plug in the new 24" iMac and let Time Machine do its stuff - it told me that it had backed up from a different computer, which I knew, but I want it to back up from this NEW 24" iMac now.


Is it OK just to let it run? Don't want to do anything that will harm any of my files, but as I say, everything has migrated over fine.


Thanks in anticipation - if I can't get help from this Forum, guess I can ring Apple direct.

iMac 24″, macOS 13.3

Posted on Apr 15, 2023 9:41 AM

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Posted on Apr 15, 2023 10:16 AM

You might be better off erasing the LaCie drive and then starting a new Time Machine backup. Otherwise you may end up with the old backups and the new backups. Which may or may not be a problem depending on how much storage is used. Eventually it will run out of space and start removing old backups but it won't touch the old backups from the previous Mac.


Alternatively, you can buy another LaCie drive and start fresh while keeping the older backups as a safety net.


To erase the LaCie open Disk Utility click the View menu and Show All Devices. Highlight the LaCie in the left-sidebar and click the Erase button. Format it with APFS as the new Time Machine uses APFS snapshots. If you format it with HFS+ it will work but not as efficiently as it will with APFS. Once erased, eject the drive, unplug it and plug it back in. Time Machine should prompt to use it as a Time Machine drive. Then just leave it attached overnight for the first initial long backup.

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7 replies
Question marked as Top-ranking reply

Apr 15, 2023 10:16 AM in response to Honeycombebeach

You might be better off erasing the LaCie drive and then starting a new Time Machine backup. Otherwise you may end up with the old backups and the new backups. Which may or may not be a problem depending on how much storage is used. Eventually it will run out of space and start removing old backups but it won't touch the old backups from the previous Mac.


Alternatively, you can buy another LaCie drive and start fresh while keeping the older backups as a safety net.


To erase the LaCie open Disk Utility click the View menu and Show All Devices. Highlight the LaCie in the left-sidebar and click the Erase button. Format it with APFS as the new Time Machine uses APFS snapshots. If you format it with HFS+ it will work but not as efficiently as it will with APFS. Once erased, eject the drive, unplug it and plug it back in. Time Machine should prompt to use it as a Time Machine drive. Then just leave it attached overnight for the first initial long backup.

Apr 15, 2023 11:20 AM in response to Honeycombebeach

You should be able to use the LaCie TM drive with your new M1. As a test do the following;


1 - connect the LaCit directly to your new iMac via one of the ports. Make sure it shows on the Desktop.

2 - hold down the Option key. go to the TM menu and select "Browse Other Backup Disks…".

3 - go back in time to a file on the Desktop and see if you can restore it to the Desktop. If you have another identical file already select the option to keep both.


If this works then you can continue to use the LaCie with the new iMac. It it doesn't work your best bet is to follow James Brickley's recommendation. You can at any time in the future do what he recommends if you don't need any of the old backups.



Apr 15, 2023 10:23 AM in response to James Brickley

Thank you so much - the other issue I have is that the cable I have for my LaCie external drive only has a USB on one end and the new 24" iMac only has the smaller ports (not that computer literate about these - sorry!). I bought a USB-C Hub with 4 USB 3.0 ports and it goes into the back of the machine, but says in the instructions "We do not recommend using this produce for charging - the main function of this product is data transmission. It only supports 5V@1A charging or less than that. The electric current that can be provided is very weak and cannot be used for fast charging of mobile phones (which I don't want to do anyway!)" so I guess I couldn't use it for doing the Time Machine backup. Sorry to be a nuisance! I have been looking on Amazon and cannot see a cable that would fit the new iMac and the LaCie external drive, although the end from the new USB C Hub fits into the LaCie. Hope you can understand all that!

BACKUPS ON TIME MACHINE

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