time machine on two drives

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Level 1

8 points

time machine on two drives

I've searched here and on the wider web and am in search of some clarification.

I want to set up 2 usb/firewire exterenal drives on my wife's iMac and use them exclusively for Time Machine. What I'd like to have happen is for Time Machine to see both drives and make backups of the iMac to each drive automagically.

I've seen posts that say 'sure, you can do this' and others that say 'you have to add the 2nd drive in TM, plug in one and only one drive, have TM do the the backup, then unplug the drive, add the 2nd, and have TM backup to that drive'.

I don't want to buy a 2nd drive until I understand the mechanics of doing the TM backup to 2 different external drives on one iMac.

Thank you for your help.

Posted on May 22, 2019 2:30 PM

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Answer 1

Best reply

Glenn Leblanc

Level 6

12,515 points

May 22, 2019 3:22 PM in response to dogugotw

Plug them in and add each disk to the TM backup list. TM will alternate between the drives for each backup. If one isn't available, it will continue with the other. There is no need to plug only one in at a time. I have mine setup to alternate between two Time Capsule drives.

As you can see in the image, I have both drives setup. During the next backup cycle, TM will choose the next drive in the list to use, or the oldest backup to update.

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Answer 2

John Galt

Level 10

142,692 points

May 22, 2019 4:40 PM in response to dogugotw

I've seen posts that say 'sure, you can do this' ...

Those are correct.

.... and others that say 'you have to add the 2nd drive in TM, plug in one and only one drive, have TM do the the backup, then unplug the drive, add the 2nd, and have TM backup to that drive'.

Those are completely off the wall. I surmise they were written by users who don't use Time Machine.

Glenn Leblanc's answer is 100% correct. Time Machine will back up to as many backup disks as you have, in sequence, if they are available. If one isn't available it will seek the next one, etc.

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