Backing up a MAC desktop

Any one of these choices would serve you well in a 4TB capacity:

• LaCie d2 - LaCie
• G-Technology G-DRIVE USB-C - G-Technology
• OWC Mercury Elite Pro - MacSales.com (OWC)

Cheers,

Jack

It is wise to buy an EHD that has 2-3 times the capacity of what you have stored on your iMac. I also strongly recommend using a OWC Mercury Elite Pro Series. Personally have had bad luck with the 3-4 LaCie drives I got. However I have some OWC Mercury Elite Pro's that are well over 10 years old. The reason I prefer the OWC drives is:

• Very competitive pricing
• Extremely high quality
• Excellent support from the vendor/manufacturer
• When the HD fails (they all eventually do, however with an OWC it take less than 5 minutes to replace the HD)

My 2¢ worth:

Drives for Time Machine should be about 2 to 3 times the size of the drive(s) you're backing up. 

I second the vote for OWC Mercury Elite Pro - MacSales.com (OWC) - I've been using one for 5 years now.

If you don't have a full 1 TB fusion drive then a 2 TB external drive would be sufficient.

Whatever external drive you get be sure to erase and format it to OS X Extended (journaled) with Ownership set to be ignored. Time Machine will then reformat it as it sees fit.

2 TB may be perfectly okay but it does not hurt to get 3 or 4 tb too.

Welcome to the Apple Support Communities.

How much data, including any external drives, do you have to backup approximately?

Jack

Your welcome and you too, please stay safe and well.