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Biro

macrumors 6502
Original poster
Jan 11, 2012
494
756
I’ve got a new M2 Max Mac Studio that I’m setting up. I figure it’s time to replace the old LaCie HDD that I was using for Time Machine with my 2019 iMac. My new Mac Studio has a 1TB internal SSD from Apple and I may add a 1TB Samsung T9 external SSD for my photos.

Will a 4TB drive be enough for Time Machine in such a scenario? I estimate that neither my internal or external drive will ever be more than half full.
 

Nermal

Moderator
Staff member
Dec 7, 2002
20,548
3,852
New Zealand
For what it's worth, I have a 1 TB internal drive and 2 TB Time Machine drive and haven't had any "you're running out of room for backups" errors. It will, of course, depend on what you're doing with your system: mine's mainly for "general use" (Web, the odd game, watching videos) and not for photo/video editing.
 
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Biro

macrumors 6502
Original poster
Jan 11, 2012
494
756
4TB should be more than enough space provided you aren't a video and photo hog.
I am not. Like I say, eventually both internal and external drives may be half full - but maybe not even that much.
 

apostolosdt

macrumors regular
Dec 29, 2021
209
147
In my opinion, it all depends on what you are trying to backup. I used to run TM on 4TB external disks. Now, I keep only the OS and the apps in the internal; all the data and files are on the Cloud—peace of mind!

However, it also depends on the kind of data. I write technical papers in LaTeX, that are ASCII files a few KB each. I am also a busy amateur photographer, and that’s a huge problem storage-wise. I keep three copies of the photos, alas!
 

Eric5h5

macrumors 68020
Dec 9, 2004
2,487
582
For what it's worth, I have a 1 TB internal drive and 2 TB Time Machine drive and haven't had any "you're running out of room for backups" errors.
You wouldn't ever get any errors like that anyway. If Time Machine runs out of space it just deletes the oldest backups. As long as the Time Machine drive is at least as big as the drive(s) it's backing up, you're good. The smaller the size delta the shorter the retention, depending on your activity and backup frequency. If you're a light user who activates Time Machine manually every few days, two half-full 1TB drives backing up to a 4TB drive could have backups going back many years. If you're constantly altering huge files and have automatic hourly backups on, that might only go back a few weeks.
 

Nermal

Moderator
Staff member
Dec 7, 2002
20,548
3,852
New Zealand
You wouldn't ever get any errors like that anyway. If Time Machine runs out of space it just deletes the oldest backups. As long as the Time Machine drive is at least as big as the drive(s) it's backing up, you're good. The smaller the size delta the shorter the retention, depending on your activity and backup frequency. If you're a light user who activates Time Machine manually every few days, two half-full 1TB drives backing up to a 4TB drive could have backups going back many years. If you're constantly altering huge files and have automatic hourly backups on, that might only go back a few weeks.
Things may have changed in newer versions of the OS, but at one point it was possible to get errors (I've run into them myself). TM tries (tried?) to keep at least one month worth of backups and would tell you if they would no longer fit.
 
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Mr.Fox

macrumors regular
Oct 9, 2020
158
85
I’ve got a new M2 Max Mac Studio that I’m setting up. I figure it’s time to replace the old LaCie HDD that I was using for Time Machine with my 2019 iMac. My new Mac Studio has a 1TB internal SSD from Apple and I may add a 1TB Samsung T9 external SSD for my photos.

Will a 4TB drive be enough for Time Machine in such a scenario? I estimate that neither my internal or external drive will ever be more than half full.
The disk needs a minimum of 6Tb, provided that the internal volume of the disk from 1tb, which will not be filled to 60%.
It is calculated very easily using the formula:
SSD/HDD size for secure storage TM = IBS + [30 * DCD + 48 7 * DCD]NM
where:
IBS = Initial backup size (GB)
NM = Number of months required to fill
DCD = Daily failure data in GBs
Suitable for both HDD and SSD, but in the latter case, if you use SSD you need to add another 500GB for a safe corridor in case of critical filling of the entire SSD to the already available volume. If it is not clear, instead of 6Tb at full capacity you should have a minimum of 6Tb+500Gb of free space.
For a RAID array with a total volume of 3Tb you should take a 12Tb disk. This is assuming that you do not process photos. The formula is as follows:
TM RAID = I (SSD/HDD) *4 ,
where:
I- the total volume of the disk (new), which has already passed the creation of a RAID array through the disk utility.
 
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Mr.Fox

macrumors regular
Oct 9, 2020
158
85
Complete nonsense; 4TB is more than enough for this case.
Well, well, well. I see you have a lot of experience in organizing uninterrupted operation of computers that run 24 hours a day, 7 days a week and 365 days a year with constant backup of everything. Try then to explain to the customer who pays money, where his information went and how to restore it. :)
 
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Apple_Robert

Contributor
Sep 21, 2012
34,252
49,419
In the middle of several books.
Well, well, well. I see you have a lot of experience in organizing uninterrupted operation of computers that run 24 hours a day, 7 days a week and 365 days a year with constant backup of everything. Try then to explain to the customer who pays money, where his information went and how to restore it. :)
The OP isn't using a NAS. His backup needs are not anywhere close to what you posted about. Do you own a Mac and actively use Time Machine or Carbon Copy Cloner?
 

Mr.Fox

macrumors regular
Oct 9, 2020
158
85
The OP isn't using a NAS. His backup needs are not anywhere close to what you posted about. Do you own a Mac and actively use Time Machine or Carbon Copy Cloner?
I have a Mac Studio M2 Ultra (24-core CPU, 76-core GPU, and 32-core Neural Engine)+ 192GB Ram+ 8TB SSD. I actively use backups and TM. I also have a workstation with AMD Ryzen Threadripper 7980X, where Mac Studio chokes and can't handle the workloads+ personal 200Tb server (HDD bought before the mining boom).
 

Apple_Robert

Contributor
Sep 21, 2012
34,252
49,419
In the middle of several books.
I have a Mac Studio M2 Ultra (24-core CPU, 76-core GPU, and 32-core Neural Engine)+ 192GB Ram+ 8TB SSD. I actively use backups and TM. I also have a workstation with AMD Ryzen Threadripper 7980X, where Mac Studio chokes and can't handle the workloads
Given that you are familiar with Macs and TM etc., your previous posting comes across as someone who isn't familiar with TM and how it works, not to mention I think you failed to take into account the OP's actual needs per the current equipment and wants. That is why I asked what I did. Telling the OP he needs 6TB of backup when he already has 4TB is overkill to say the least. He would be wasting money, given his post, in my opinion.
 

Mr.Fox

macrumors regular
Oct 9, 2020
158
85
Given that you are familiar with Macs and TM etc., your previous posting comes across as someone who isn't familiar with TM and how it works, not to mention I think you failed to take into account the OP's actual needs per the current equipment and wants. That is why I asked what I did. Telling the OP he needs 6TB of backup when he already has 4TB is overkill to say the least. He would be wasting money, given his post, in my opinion.
You're worried about every dime? 200 bucks for a disk so you don't have to worry about anything? A miser pays twice....
 

Eric5h5

macrumors 68020
Dec 9, 2004
2,487
582
Throwing money away for literally no reason is just stupid, though.
Well, well, well. I see you have a lot of experience in organizing uninterrupted operation of computers that run 24 hours a day, 7 days a week and 365 days a year with constant backup of everything. Try then to explain to the customer who pays money, where his information went and how to restore it. :)
I see you like posting stuff that has no relation to the topic being discussed. Try re-reading the first post, understand it, then write something actually relevant. The question is, is a 4TB Time Machine drive good enough for maybe 1TB of stuff, not "how to run a data center." Have some perspective, please.
 
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splifingate

macrumors 65816
Nov 27, 2013
1,180
970
ATL
I’ve got a new M2 Max Mac Studio that I’m setting up. I figure it’s time to replace the old LaCie HDD that I was using for Time Machine with my 2019 iMac. My new Mac Studio has a 1TB internal SSD from Apple and I may add a 1TB Samsung T9 external SSD for my photos.

Will a 4TB drive be enough for Time Machine in such a scenario? I estimate that neither my internal or external drive will ever be more than half full.

Entirely sufficient.

You may find that older stores are let-go after some point in, er, Time, but that's just the way of things.

If you're finding that you are needing to step-back in time more than months-ago, you have larger fish to fry.
 

ItWasNotMe

macrumors 6502
Dec 1, 2012
439
304
Entirely sufficient.

You may find that older stores are let-go after some point in, er, Time, but that's just the way of things.

If you're finding that you are needing to step-back in time more than months-ago, you have larger fish to fry.

Completely agree.

A key point is Time Machine is NOT an archive. It decides when things are deleted, not you. If you absolutely need to keep a file, do something else as well.

For example, if you want to restore a file that you created five years ago (e.g. a photo) that you may have accidentally deleted four years ago, Time Machine is not what you should be relying on. Depending on how Time Machine has decided to trim it's history, it might be there, it might not.
 

Alameda

macrumors 6502a
Jun 22, 2012
851
321
I think 4TB is enough, though larger drives don’t cost much more.

The bigger problem is that my experience with Time Machine is that it begins to fail over time, and you need to delete the Time Machine backup and start a new one at some point, perhaps once a year, depending on how much your files change. I don’t know if Apple’s ever fixed that.

The other thing is that the largest cause of data loss is not drive failure but theft. If someone breaks into your home, they will steal your backup drive along with your laptop, which could be catastrophic for you if it holds business data. You need to get your data offsite, somehow. Not necessarily daily, depending on your situation.
 

Wando64

macrumors 68020
Jul 11, 2013
2,095
2,624
Well, well, well. I see you have a lot of experience in organizing uninterrupted operation of computers that run 24 hours a day, 7 days a week and 365 days a year with constant backup of everything. Try then to explain to the customer who pays money, where his information went and how to restore it. :)

What on earth makes you think this is relevant in a post about the size of a TM?
Besides, why assuming that other people have no experience of something or other?

I am not going to bore you with my experience because what is relevant here is what Apple says, and Apple says that the Time Machine disk should be ideally (their word) at least twice that of the disks they are backing up.
It is not difficult: 2 + 2 = 4

Personal experience tells me that you can get away with less, depending on the occupancy of the source disks, the type of data stored on them and your personal expectation of how much rollback you need.
 

MRxROBOT

macrumors 6502a
Apr 14, 2016
785
815
01000011 01000001
I’ve got a new M2 Max Mac Studio that I’m setting up. I figure it’s time to replace the old LaCie HDD that I was using for Time Machine with my 2019 iMac. My new Mac Studio has a 1TB internal SSD from Apple and I may add a 1TB Samsung T9 external SSD for my photos.

Will a 4TB drive be enough for Time Machine in such a scenario? I estimate that neither my internal or external drive will ever be more than half full.
4TB is plenty for your use case and you could stop there. Everything I'm writing below is what I would recommend to anybody who approached me in person about this, so feel free to ignore the bit below if you're happy with the one 4TB.

I would recommend picking up another drive. From what I gathered in your initial post, you could likely get away with just a 2TB and you can setup as an additional daily backup schedule. I like having redundancy personally. If you're already backing up in the cloud, you could get away without the second drive (not ideal but better than just 1).

Im trying not to overwhelm you, I just don't want you in a position where you lose your photos or data. I personally run everything in raid 1 at home, every drive has a mirrored copy. So my 56TB DAS is more like 28TB and I'm okay with that loss of drive space because I know that if any single drive crashes, ive got a backup that leaves me without any disruption or anxiety.
 

JamesMay82

macrumors regular
Jul 21, 2023
121
124
I’ve got a new M2 Max Mac Studio that I’m setting up. I figure it’s time to replace the old LaCie HDD that I was using for Time Machine with my 2019 iMac. My new Mac Studio has a 1TB internal SSD from Apple and I may add a 1TB Samsung T9 external SSD for my photos.

Will a 4TB drive be enough for Time Machine in such a scenario? I estimate that neither my internal or external drive will ever be more than half full.
which lacie do you have? I have a 2big that's probably 6 years old which has failed once but I just replaced the disks and now I use it for my time machine back up and it works fine. I try to keep as much on my internal drive so I can just back it up with Time Machine rather than have it scattered across multiple externals.
 

SpanishAppleNerd

macrumors regular
Dec 7, 2023
119
92
Badajoz
FWIW, I have a 2 TB external drive for backuping a 1 TB M3 iMac + 2TB iCloud for when I get video and photo editing crazy... so that's 3 TB of possible backups + another 3 or 9 if I need to increase my cloud storage. So for you OP, being a case close to mine, I think that you're well served
 
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