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h.gilbert

macrumors 6502a
Original poster
Nov 17, 2022
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Bordeaux
I have an M1 Air with a 256GB drive. I also have a 1TB external SSD drive. If I use that drive for time machine am I able to access that drive as a 'normal' drive still to store a few random files or to move files between devices. Or, do I need to partition the external drive to something like 750GB and 250GB, and let time machine use the 750GB partition?
 

scouser75

macrumors 68030
Oct 7, 2008
2,951
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I have an M1 Air with a 256GB drive. I also have a 1TB external SSD drive. If I use that drive for time machine am I able to access that drive as a 'normal' drive still to store a few random files or to move files between devices. Or, do I need to partition the external drive to something like 750GB and 250GB, and let time machine use the 750GB partition?
I've asked the same Q on the link mobomac gave above. Head on over 🙂
 
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h.gilbert

macrumors 6502a
Original poster
Nov 17, 2022
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Almost got it... just one thing what order should I do this in? Open up TM and select my external SSD, let it back up, and then go into disk utility and create another volume... or the other way round?

(wanting to use one external SSD for TM while also being able to use part of it for moving files and whatnot)
 

Macky-Mac

macrumors 68040
May 18, 2004
3,700
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I've been using external drives for TM for years and have always also used them for manual back ups of odds and ends of files....I've never partitioned the drives and I've never had a problem.
 

apostolosdt

macrumors 6502
Dec 29, 2021
324
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Nothing to add, all posts above cover OP’s question. Keep in mind, though, that Apple doesn’t recommend that.
 
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ChrisA

macrumors G5
Jan 5, 2006
12,918
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Redondo Beach, California
Time Machine will continue writing data to the external drive, or partition until it fills that space completely. Then it will delete the oldest version of your files to make room for the newer files. It will take a long time to fill a 1TB drive, but eventually it will. If the drive is full, you will not be able to use it for other purposes. A "mature" TM drive is always full.

So what you might do is make a container, like a partition and use that for Time Machine. TM then will only fill up that partition.

As for in what order? Obviously, you can't give TM the partition until after you make it.

Others have said TM will format the drive. They are mistaken, TM will not change anything outside of the partition you give it.

Why use a physical SSD to move data? YOu can always use a network connection and with a new Mac, all you data is by default already on iCloud. You can download this data to any computer from iCloud.

Use network shares, iCloud or even Thunderbolt networking to move data.
 
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NoBoMac

Moderator
Staff member
Jul 1, 2014
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Others have said TM will format the drive. They are mistaken, TM will not change anything outside of the partition you give it.

I’ll admit that I have not formatted a new drive for TM in a while, but in the past, if you formatted a drive as APFS, made two volumes, one for TM and another for general, and told TM to use the TM one, it would erase both and start fresh as TM volume needs to be case sensitive and have an APFS role of Backup assigned.

Went through this a couple of times as wanting to assign encryption to TM volume before starting TM for a new drive before I realized it‘s a “feature”.

Some discussion around this here:

 

BigMcGuire

Cancelled
Jan 10, 2012
9,832
14,032
I’ll admit that I have not formatted a new drive for TM in a while, but in the past, if you formatted a drive as APFS, made two volumes, one for TM and another for general, and told TM to use the TM one, it would erase both and start fresh as TM volume needs to be case sensitive and have an APFS role of Backup assigned.

Went through this a couple of times as wanting to assign encryption to TM volume before starting TM for a new drive before I realized it‘s a “feature”.

Some discussion around this here:

That's what I do.

APFS Encrypted. 2 Volumes, one for my manual backups - Parallels backups, and one for my Time Machine. It asked me the password when I chose the volume as a TM volume and I was good to go.

Kind of cool how they both use the 4TB as a pool of available data without having to specify space for each partition. I really like APFS.

1691765358158.jpeg
 

h.gilbert

macrumors 6502a
Original poster
Nov 17, 2022
718
1,263
Bordeaux
Sorry I'm so confused now... Do I add another volume first or TM first?

Also, forgot to ask, is TM suitable for a permanently attached drive? As in I use my laptop very much like a laptop and would just like to plug in the TM drive every Sunday or so and let it do its thing.
 

Fishrrman

macrumors Penryn
Feb 20, 2009
29,242
13,315
Use the time machine backup drive for tm only.

If you need to transfer files around, get a USB flash drive of sufficient capacity. If you're moving files between the Mac and a PC, format it to exFAT. If it's Mac-only, use HFS+.

If you need an external drive on which to store files "off-Mac", get either a USB hard drive or USB SSD.

I'd suggest something like this:
(that's a great price on it right now)

If it's a platter-based hard drive, format it to HFS+ ("Mac OS extended, journaling enabled, GUID partition format").
If it's an SSD, you can use APFS if you wish -- but for a non-booting drive that is used for data only (and not a tm backup), I'd still suggest HFS+ as "the better way to go".
 
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ChrisA

macrumors G5
Jan 5, 2006
12,918
2,170
Redondo Beach, California
I’ll admit that I have not formatted a new drive for TM in a while, but in the past, if you formatted a drive as APFS, made two volumes, one for TM and another for general, and told TM to use the TM one, it would erase both and start fresh as TM volume needs to be case sensitive and have an APFS role of Backup assigned.

Went through this a couple of times as wanting to assign encryption to TM volume before starting TM for a new drive before I realized it‘s a “feature”.

Some discussion around this here:

Volumes and partitions are different. With APFS a volume might include multiple disks. It is a logical thing. A partition is pert of one drive.

But all this discussion is moot. The best practice is to never use a Time machine drive for any other purpose.
 
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HDFan

Contributor
Jun 30, 2007
7,290
3,341
the best practice is to never use a Time machine drive for any other purpose.
Yes. If you can it is better to not partition the external drive. In a 3-2-1 backup strategy you likely would be rotating the drive to off-site storage and would lose access to data on the other partition. TM should only be 1 of your 3 backups since it tends to fail.

If it's a platter-based hard drive, format it to HFS+

Not an option. TM formats to APFS.

Better to use a hard disk for TM. For the same money get more storage which means greater history is preserved. The charge on an SSD may deteriorate faster than HD encoding when storage for long periods of time. An SSD can actually be less reliable in some cases than a physical disk. You are paying for SSD speeds which you don't need with a backup utility that runs in the background.
 
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