Need new backup drives for my new MBP M1 Pro

Hmm… It seems I have more data than I thought after moving my external Photos library to my new internal 2 TB drive. I thought it would be under 1 TB, but it says I only have 880 GB of free space left after the move, so I must have a bit over 1 TB.

Unfortunately both my Time Machine drive and CCC drive are both 1 TB drives. So I can’t make a backup to either now.

Looking at Amazon, can get delivery tomorrow on 2 TB or 4 TB WD portable hard drives. I guess 2 TB is enough for CCC because it’s just making a clone. But wondering if I should spring for 4 TB for Time Machine for older versions.

A semi-expected-but-not-so-soon extra expense.

Rule of thumb for Time Machine is at least 3 times bigger than the data to be backed up, so that means the 4TB.


I’d agree with @alvarnell. You don’t want your TM drive to be too tight.

And compared to what we just laid down for these fancy new 14" MBPs, the extra few $ for a larger HDD is peanuts anyway. :wink:

You might be interested in this current deal.

$260 on a 14TB external hard drive right now at Best Buy

The drive mechanism inside is
CMR Helium filled 7200 rpm (all good things)

I really like WD. Unfortunately there are no Best Buys here in Japan. So my best choice is probably to order a drive from Amazon Japan. 14 TB sounds amazing, but is probably more than I need.

I would say at least 4 TB for Time Machine. But really 2 TB for CCC ought to be enough since it’s just a daily clone.

I will concentrate on getting Backblaze working tonight in the meanwhile. Perhaps even get a little work done on the side. :slight_smile:

  1. With respect to cloning, if you are deleting all files on the clone that no longer exist on the parent drive, then the clone volume needs to be no larger than the parent. If you are only creating a data clone rather than trying to make a bootable one, you need even less space, as you will not be copying any of the read-only volumes on the driver.

  2. Note that in considering a base number for the time-machine drive, consider what the true capacity of the drive is; you should never totally fill a working startup drive–you need to leave some working space for memory swapping, temp working files, and caches. None of those elements should be in the clone or be archived. I know that I start getting uncomfortable when I have only 20% free space left on a boot drive.

With regards to (1) I’m doing the former so I don’t need a drive for that larger than the internal drive.

For (2) I may get a 4 TB drive to start, I guess.