Backing up two Macbooks with Time Capsule

I can use the Time Capsule disk (single partition) in conjunction with CCC or SD. I don't want to junk a very expensive 3TB hard disk! Do either or both of these backup apps resolve the disk full issue?

I have not used SD for a long while so cannot speak to it. BUT it should work.

CCC is a more competent solution.

It works entirely differently to Time Machine.. and it is important for you to understand that.

CCC is a cloner.. it is there in the name.. (SD is also a cloner).

What it does first and foremost is maintain a clone of your computer disk.

If you delete a file from the computer it will be deleted on the clone.. add a file on the computer it will be added to the clone. CCC will therefore always maintain a clone of exactly the same size as the full install on the Mac disk.

Time Machine is different.. it is designed to maintain a history of your computer for as long as the disk capacity lasts.. that means it just grows and grows. The principle was that when the disk is full it will start deleting oldest files.. as you know it fails miserably now in that mission.

CCC can be configured to keep a cache of recent files.. and you can set that size yourself.

So size is always under control.

First things first.

it's not obvious how to partition the disk in Time Capsule.

No that is not possible. The TC is controlled by the internal firmware of the TC.. and no partitioning is available.

Nor a lot of other functions.. like limiting usage of disk space per user or computer etc etc.

Time machine is supposed to be clever enough to delete the oldest backups to make room for new ones.

It has never worked well (at all) on the last few Mac OS and Catalina worst of all.

And partitioning would also not help.. even if you dedicate the disk to a single Mac it still will fail to delete old backups once it fills the drive.

Just FYI sparsebundle (backupbundle in Catalina) is a virtual disk and so a virtual partition if you like. We used to be able to control the size to some extent but that is now very unreliable.

I'm also not convinced that all, or any of the backups are accessible.

wow .. you have got it 3/3.. correct.. since Catalina Time Machine is pretty much broken.. DO NOT TRUST IT. Backup to local drive are OK.. but to network and specifically the Time Capsule are a no go.

unless you feel urgent need to recover.. erase the TC and start over.. but I strongly recommend using a different backup software like Carbon Copy Cloner. SuperDuper is also popular. You can archive the TC before you erase but this is only for last resort.

You can create sparsebundle for CCC as target on the TC and backup both your computer to separate sparsebundles. It is far more reliable than Time Machine and one license covers all the computers in your household. (Disclosure.. I have no connection and pays for a license like everyone else).

Time machine is supposed to be clever enough to delete the oldest backups to make room for new ones.

That's the theory. In practice, things don't work all that well when the Time Capsule is close to being full and a new backup is a bit larger than normal. Then, Time Machine cannot delete enough old backups to make room for the new backup. Of course, Apple does not tell you about small details like this.

When this occurs, you have two options:

1) Connect a USB drive to the USB port on the Time Capsule and copy or "archive" all of the data on the Time Capsule drive over to the USB drive. Then, erase the Time Capsule drive and start over again with new backups of your Macs.

2) If you don't really need all the old backups from many weeks, months and even years going back in time......(few of us ever do)......erase the Time Capsule drive and start over again with new backups of each Mac.

I've been told that if you try to backup two or more mac devices to a single partition it can't decide which old backups to delete, so it remains full and the new backups fail.

You got incorrect information. Time Machine will try to delete the oldest backups of the Mac that is currently trying to back up.

I'm also not convinced that all, or any of the backups are accessible. Most of the backup dates/times indicated in the right hand side bar when entering Time Machine are greyed out.

If you are using WiFi to connect the Mac to the Time Capsule, it might take 15-20 minutes or more for all of the old backups to fully load. Sometimes, Time Machine will perform a check on the integrity of the backups before they display. This will take even longer.

When I've changed the backup device to an external hard drive it produces folders for each day and the full backup folder tree is accessible directly.

That is because Time Machine backs up differently to a "network drive" like the Time Capsule than it does to a "local drive"......one that is connected directly to a Mac. Time Machine backs up to a special type of file called a "sparsebundle" on a Time Capsule. If you are running the Catalina operating system, Time Machine backs up to a similar type of file called a "backupbundle".

Time Machine backs up to normal looking folder called "Backups.backupdb" on a local drive connected directly to a Mac.

You can see the same type of folder layout in the Time Machine backups of a Mac on the Time Capsule, but it takes some additional steps to drill down through some layers before the dated folders will appear. If you are curious, we can provide the steps to do this, but it won't help the current issue of not enough free space on the Time Capsule drive.

However, it's not obvious how to partition the disk in Time Capsule. It doesn't seem to appear in Disk Utility. Is this possible?

The only way to partition the disk on a Time Capsule is physically remove the drive from the Time Capsule, place it in a caddy or enclosure and then connect that device directly to your Mac. Not an easy task, even for a technician. But, even if you do this, you will still face the issue of the Time Capsule running out of space at some point with not enough space for new backups. Nature of the beast, I am afraid.

I think, from what you say I can use the Time Capsule disk (single partition) in conjunction with CCC or SD.

Yes you can. One of the advantages of backing up this way is that you can do so over the WiFi network, so the Time Capsule does not need to be physically connected to the Mac, as a normal USB drive would be.

Do either or both of these backup apps resolve the disk full issue?

No, but you only need as much space as the current amount of data on your Mac's hard drive with Carbon Copy Cloner or SuperDuper.

As a matter of interest, when I plug my new Seagate external drive into the Time Capsule USB port, although it is accessible, the TC lights continuously flashes orange, so it doesn't seem to be a happy bunny! I've used the Seagate with Time machine since the TC became full

Open AirPort Utility on your Mac

Click on the picture of the Time Capsule and a smaller window will appear

Look for "Status" in that window and click on the small amber dot for more info about the issue