Time Machine: first backup is way bigger than total backup size

[PCFan]

This is my first backup. When I first started it about a week ago, it initially said the total was about 94.50GB. After days of letting it do its thing, it FINALLY got there! Here's the thing though - it's still backing up! It's now at 131GB and still going, but doesn't even say out of how much or how much time remaining!

Any idea why this is happening? It just says "Backed up" - no "out of" and no "Calculating time remaining"

Even when clicking on "Options..." it says the total backup is 101.82GB

The weirdest part is that I'm only using 100GB in total storage... which is less than the current backup size.

I'm backing up using a 1TB WD My Passport plugged into an AirPort Extreme.

 

[Daverich4]

Are you encrypting the backup? The first time I did that the backup took 4 days.

 

[PCFan]

Are you encrypting the backup? The first time I did that the backup took 4 days.

I don't think so... How could I check?

 

[Daverich4]

I don't think so... How could I check?

How to encrypt your Time Machine backups

If an extra layer of security, you can encrypt your Mac backup data using the built-in Time Machine app. Here's how to do it.

www.imore.com

 

[PCFan]

How to encrypt your Time Machine backups

If an extra layer of security, you can encrypt your Mac backup data using the built-in Time Machine app. Here's how to do it.

www.imore.com

Nope, not encrypted. The issue isn't really the time it takes, but mostly how it the backup is still going (at 152GB right now) when the initial estimated total was like 94GB...

 

[KALLT]

Maybe you should quit the backup and try again.

 

[CoastalOR]

This is my first backup. When I first started it about a week ago, it initially said the total was about 94.50GB. After days of letting it do its thing, it FINALLY got there! Here's the thing though - it's still backing up! It's now at 131GB and still going, but doesn't even say out of how much or how much time remaining!

Any idea why this is happening? It just says "Backed up" - no "out of" and no "Calculating time remaining"


Even when clicking on "Options..." it says the total backup is 101.82GB
View attachment 912699

The weirdest part is that I'm only using 100GB in total storage... which is less than the current backup size.


I'm backing up using a 1TB WD My Passport plugged into an AirPort Extreme.

Does your WD My Passport have any other Partitions/Volumes besides the one you are using for Time Machine? It is possible that Time Machine is backing up other attached drives/volumes since none are excluded.

 

[throAU]

Couple of tips

1. Time machine includes history, so you can get back old versions of files. If you have deleted files, etc. those will still be included as they would have been tracked via local (on machine) backups before being pushed to time machine. E.g., if you deleted 50 GB of files, they will still be in your time machine backup, even if you removed them from trash, if time machine local backups as enabled (as they are by default if you have free space)!
2. Time machine runs as a "background task" and by default doesn't get a lot of processor time to work quickly. For your initial backup you can speed it up by disabling background task throttling on your Mac. this will give time machine far more CPU priority to get the job done faster. note: this will make it cause more heat/noise/etc. but for the first backup it will help get it out of the way
3. exclude things that you don't need in there such as iCloud content, iTunes library, etc. If you run VMs on your machine I'd suggest excluding them as well and back them up some other way (if required). Otherwise your backups will be huge.

To alter background task priority on your Mac (speed it up), using the terminal type in:

• sudo sysctl debug.lowpri_throttle_enabled=0

To set things back to normal (as out of the box) so time machine doesn't slow things down, create undue heat/noise/etc.

• sudo sysctl debug.lowpri_throttle_enabled=1

 

[PCFan]

Does your WD My Passport have any other Partitions/Volumes besides the one you are using for Time Machine? It is possible that Time Machine is backing up other attached drives/volumes since none are excluded.

That's interesting... my WD My Passport does not have any partitions or volumes, but it does have some files I manually backed up and it has the Time Machine backup of another Mac. Are you saying it's backing those up as well? I tried excluding the whole drive, but it keeps disappearing from the list even after I click "Save"...
[automerge]1588953826[/automerge]

Couple of tips

1. Time machine includes history, so you can get back old versions of files. If you have deleted files, etc. those will still be included as they would have been tracked via local (on machine) backups before being pushed to time machine. E.g., if you deleted 50 GB of files, they will still be in your time machine backup, even if you removed them from trash, if time machine local backups as enabled (as they are by default if you have free space)!
2. Time machine runs as a "background task" and by default doesn't get a lot of processor time to work quickly. For your initial backup you can speed it up by disabling background task throttling on your Mac. this will give time machine far more CPU priority to get the job done faster. note: this will make it cause more heat/noise/etc. but for the first backup it will help get it out of the way
3. exclude things that you don't need in there such as iCloud content, iTunes library, etc. If you run VMs on your machine I'd suggest excluding them as well and back them up some other way (if required). Otherwise your backups will be huge.

To alter background task priority on your Mac (speed it up), using the terminal type in:

• sudo sysctl debug.lowpri_throttle_enabled=0

To set things back to normal (as out of the box) so time machine doesn't slow things down, create undue heat/noise/etc.

• sudo sysctl debug.lowpri_throttle_enabled=1

Thanks for the tips. The issue isn't really how slow it is, but more how there is no ETA or estimated total of the backup... It usually says something like "Backed up 12GB out of 94.50GB" or something, whilst now it just says "Backed Up 152GB"...

 

[api76]

I have exactly the same problem. I have about 1.2TB of data to back up and over 4 days my Time Machine backup grew to 2TB before it failed saying the backup disk wasn't big enough.

 

[cynics]

I have exactly the same problem. I have about 1.2TB of data to back up and over 4 days my Time Machine backup grew to 2TB before it failed saying the backup disk wasn't big enough.

Possible have a large chunk of data that TM can't directly access to address modifications?

For example, if you use a virtual machine for Windows/Linux/Whatever due to limited access if you make modification Time Machine will often backup another copy of the ENTIRE virtual machine.

Anything like that?

 

[matram]

Try the following command in terminal, it will give you a verbose log of what is happening during backup, including estimation of needed disk space for the backup.

log show --style compact --predicate 'subsystem == "com.apple.TimeMachine"' --info --last 3h

If TM runs out of space it will try to prune the backups, by removing older backups (assuming there are any). This will also be visible in the log.

If the backup takes a long time, in my experience it is one of two things, either TM is doing a full disc scan because it is the first backup (or it was a long time since you last backed up) OR TM is pruning backups on the disk to free space.

For me with 1TB of data a full scan takes a couple of hours on internal SSD. On a network connected disk my experience is that it takes at least 10x longer to scan the disc or write a backup. I have scrapped my NAS and now back up to directly connected TB-disks to get around this.

 

[posguy99]

For example, if you use a virtual machine for Windows/Linux/Whatever due to limited access if you make modification Time Machine will often backup another copy of the ENTIRE virtual machine.

You really want to exclude things like VMs from Time Machine. Make a static copy of them somewhere so you can get them back as required, but don't back up a possibly multi-gigabyte volume repeatedly because a few hundred megabytes changed in the middle of it.

 

[lostless]

You’ve also used your computer as it was backing up. Especially as a first backup. It will continue to backup all the file/apps etc you’ve added/changed since the backup started. I’ve noticed this many times if im doing some video editing or whatever uses a lot of data during a backup. I’m pretty sure that is what you are seeing.

 

[ericolson]

I have exactly the same problem. I have about 1.2TB of data to back up and over 4 days my Time Machine backup grew to 2TB before it failed saying the backup disk wasn't big enough.

Are you possibly writing the backup file to a place that gets backed up? If your backup is going to /Users/gizmo and you're backing up /Users, then the backup becomes part of itself and will likely take forever to back up.