Time Machine wired, then wireless?

[mcdj]

I started making a fresh backup of my wife’s MacBook Air on Time Machine wirelessly, as I have done for years. I’m using a new 8TB SSD with an OWC enclosure connected to a new Mac mini M4.

With only 50% of the back up complete, Time Machine was telling me it was going to take another 22 hours. My wife needed to take her computer to work. So we needed to stop the back up.

When she got back from work, it’s still said another 22 hours, and she would need to take a computer to work again the next day, so I decided to scrap this back up completely and connect the SSD directly to her computer via USB.

For some reason, Mac OS decided that the partial back up we had started would not be added to. It asked me if I wanted to back up to the SSD plugged in, along with the backup created wirelessly. In other words, it was going to create a new back up and also write to the back up that was previously started. Obviously, I didn’t want that. So I formatted the disc and made a fresh back up, which was completed very quickly.

Then I stopped Time Machine, ejected the drive, and plugged it back into the Mac mini, hoping that her computer would see it and continue to back up to incrementally.

Unfortunately, the reverse situation occurred, whereby it asked me if I wanted to write to a new back up as well as the back up already on the drive. Her computer has no problem seeing the drive to back up to, but it doesn’t seem to recognize the sparse bundle as one that it has written already.

I was never asked if I wanted to inherit a back up. I don’t have much hair to pull out, but this is driving me nuts. There has to be some way I can make a fast initial back up, wired, and then plug the drive back into the Mac mini and continue with incremental wireless backups. Can anybody point me to a way to do this?

 

[cleanton]

There should be a setting to describe the path to backup. Find a setting to redescribe the wireless path on the time machine app.

 

[cleanton]

From time machine settings add new time machine destination.

 

[mcdj]

That starts an entirely new backup from scratch.

 

[Brian33]

Time Machine uses different storage layouts depending upon the type of connection to the back up destination drive. If the drive is directly-attached to the computer being backed up (for example, via USB or thunderbolt), a folder and snapshot structure using APFS is used for the back up.

Alternatively, if the drive is attached to a remote computer, NAS, or router, and accessed over a network, then Time Machine must create a sparse bundle disk image on the drive. This is because network-attached volumes are accessed using the SMB protocol, and features of the underlying file system are unavailable (and in fact may be formatted in Linux or Windows formats). In this case, Time Machine creates a disk image, which contains a virtual volume formatted as APFS to provide the needed file system features.

I doubt there is a practical method to convert from one type to the other, and I have never read of anyone doing so.

I suggest you start a new network-attached back up. Stop it when she needs to take the laptop, and restart it when the laptop returns. Time Machine will not copy any files that have been successfully backed up and are unchanged. I think you could do this multiple times, as it may take several days to complete the first backup. Subsequent back ups will generally be pretty quick.

 

[FreakinEurekan]

I agree with @Brian33, USB and wireless are not cross-compatible.

USB backups go to a backups.backupdb folder
Wireless backups go to a sparse file.

 

[Weaselboy]

@mcdj You should be able to open the sparse bundle then drag the backups file out of the bundle and to the base of the drive, then use the backups file to continue the backup over USB.

 

[eas]

@mcdj You should be able to open the sparse bundle then drag the backups file out of the bundle and to the base of the drive, then use the backups file to continue the backup over USB.

There isn't a backups file with modern Time Machine backups. There are APFS snapshots. They can't be moved to another volume.

 

[smirking]

How large is the filesystem that needs to be backed up? I was in this exact scenario a short while ago as I completely updated my setup. I had given up on Wifi backups to Time Machine because the slow speed just made it impossible.

Well, I discovered that I had problems stacked on top of problems.

1) I thought I had Cat 6 Ethernet cables. Nope. They were Cat 5's that limited the speed into my Time Machine drive to a measly 100Mbps. I had effective copy speeds of about 8MB/s. Backing up my 1.5TB filesystem would take 2 or more days like this.

2) Even after fixing that, I still couldn't get more than 20MB/s speed from my outdated Airport Extreme time capsule even over Ethernet. I'm still puzzled about why that is, but it doesn't matter because...

I replaced my entire obsolete setup with a new WiFi 6 router and a NAS. I'm now able to get write speeds of over 80MB/s wirelessly. Even backing up my entire filesystem is not an overwhelming burden. It takes around 8 hours or so.

I originally planned to attempt a wired backup and then continue it over WiFi, but now that I've fixed my setup, it's not worth even trying. My networked write speed is almost up to par with the wired speed I can get with an old spec slow "Green" HDD.