Continue with a new hardrive for TM backups

[MacUse-R]

So my current external Time machine backup hardrive which is connected to the USB port on the Apple Time Capsule is full (and so is the internal hard drive of the Time capsule as well).

So I want to use the new hard drive with the time capsule, right now I have both the old full external HD and the new external HD connected to the TC USB port through a powered USB hub (since the Time Capsule only has 1 USB port).
My MacBook Pro and Time Machine is recognising both external hard drives

So how can I continue to use the new hard drive, meaning so that it will only backup new changes on the computer?
I guess normally if I choose to use the new hard drive in Time machine settings it will backup the whole computer since its a empty hard drive, but I don't want it to do that since it will take up a lot of space.
I just want it to continue from the old external TM hard drive, so it only backups changes made since the last backup on the old HD.

How do i do that? Haven't really tried anything yet. I guess I will have to get the TM to recognise both connected drives as 1 single drive, or how does it work?

 

[Dave_H]

How come a TM disk/drive is full? Normally the oldest backup is deleted to make room for the new ones. Unless I don't understand the question.

 

[chabig]

So my current external Time machine backup hardrive which is connected to the USB port on the Apple Time Capsule is full (and so is the internal hard drive of the Time capsule as well).

You don’t have to get a new drive unless you really want to. Time Machine will automatically prune its backups to continue using the “full” drive.

 

[pshufd]

This isn't your case but I do a full backup to the TM disk when I get a new one. One of them is about a year old and the other a month old; and they are kept in different physical locations in case of a disaster.

 

[Fishrrman]

Clean out the old backups on the Time Capsule.

I'd get an external drive, anyway.
Then use either CarbonCopyCloner or SuperDuper to create a bootable cloned backup on the external drive.

Now you have a fully-bootable-to-the-finder backup for emergencies.
It will serve you BETTER THAN any TM backup!

 

[treekram]

So my current external Time machine backup hardrive which is connected to the USB port on the Apple Time Capsule is full (and so is the internal hard drive of the Time capsule as well).

So I want to use the new hard drive with the time capsule, right now I have both the old full external HD and the new external HD connected to the TC USB port through a powered USB hub (since the Time Capsule only has 1 USB port).
My MacBook Pro and Time Machine is recognising both external hard drives

So how can I continue to use the new hard drive, meaning so that it will only backup new changes on the computer?
I guess normally if I choose to use the new hard drive in Time machine settings it will backup the whole computer since its a empty hard drive, but I don't want it to do that since it will take up a lot of space.
I just want it to continue from the old external TM hard drive, so it only backups changes made since the last backup on the old HD.

How do i do that? Haven't really tried anything yet. I guess I will have to get the TM to recognise both connected drives as 1 single drive, or how does it work?

Having TM prune the old backups as a disk gets full takes a lot of time but whether it's noticeable or not depends on your particular situation. If you are willing to prune it may be better to start a manual prune and let TM do it's work overnight.

It sounds like you want to fuse two TM backup disks together. From what I see on the web, nobody's come up with a way to do that. Conceivably, you can fuse two disks together using file links but the problem with TM is that it is proprietary so if you go outside the well-established norms that Apple sets, you can't be sure that it will work. So the problem is that TM machine stores information on the backup on a disk-wide basis on each disk used by TM. Then, there is a folder for the specific computer that uses a TM backup and under that the specific directories representing a backup date/time. If there is interconnected information between these components (and there almost surely is), if you try to mix one TM backup with another, it's not likely to work.

If your new HDD is bigger than your old HDD and you want to copy over the data - that can be done but that has issues in Mojave which is being discussed in the following thread:
https://forums.macrumors.com/threads/copying-time-machine-folder-to-another-hdd.2171572/

 

[pshufd]

The other issue in fusing two disks is that they rarely fail together. So you may have an unusable backup if either disk fails.

 

[Painter2002]

I agree with the sentiments of most others that have posted here. If you are using Time Machine, I’d just use the time capsule or one external drive and let time Machine do it’s thing. Once the Time Machine drive is full it will cut out older images to allow for new ones to be saved. Honestly you probably have years worth of backups on your machine, not likely you will ever need your oldest backups.

Having said that, after recently wiping and reinstalling MacOS and bootcamp ok my MacBook Pro, I might be trying Carbon Copy Cleaner or something similar as I got tired of the Time Machine making local backups taking space on my laptop. There should be an option to turn it off, which after Mojave (or maybe it was High Sierra) you cant even use a command line to turn off. My laptop is always home, so it doesn’t need the local backups.

 

[MacUse-R]

Thanks for the answers, maybe i forgot to write some crucial info in my first post, yes i´m aware that TM deletes the oldest backups, but that seems to not be the case for me since Time machine refuses to currently do backups since it says that I don't have enough disk space left on my backup drive? It says it needs 236 GB to do the backup but that I only have 130 GB left on my backup drive. So I guess it doesn't delete the oldest one automatically? In time machine settings it shows an red exclamation mark which gives the message about not having enough disk space?

Now that I think about it maybe it´s because the backup drive has a too small size, the external backup drive currently only holds 1 full backup. Unfortunately the new backup drive which I wanted to fuse with the old one is also small, thats the exact reason why i didn't want to start from scratch with the new backup drive and be forced to backup the whole MacBook Pro on the new backup drive, since it would have taken to much of the disk space.

I guess i have to forget about the "fusion" of the 2 external drives. I think my only solution seems to be to buy a new bigger external hard drive, like at least a 4TB or more?

 

[pshufd]

Thanks for the answers, maybe i forgot to write some crucial info in my first post, yes i´m aware that TM deletes the oldest backups, but that seems to not be the case for me since Time machine refuses to currently do backups since it says that I don't have enough disk space left on my backup drive? It says it needs 236 GB to do the backup but that I only have 130 GB left on my backup drive. So I guess it doesn't delete the oldest one automatically? In time machine settings it shows an red exclamation mark which gives the message about not having enough disk space?

Now that I think about it maybe it´s because the backup drive has a too small size, the external backup drive currently only holds 1 full backup. Unfortunately the new backup drive which I wanted to fuse with the old one is also small, thats the exact reason why i didn't want to start from scratch with the new backup drive and be forced to backup the whole MacBook Pro on the new backup drive, since it would have taken to much of the disk space.

I guess i have to forget about the "fusion" of the 2 external drives. I think my only solution seems to be to buy a new bigger external hard drive, like at least a 4TB or more?

My current TM disks are 4 and 8 respectively. These backup two systems so there should be plenty of space. 8 is probably the sweet spot for $/GB and it would be nice to not have to deal with this for the next ten years.