How can I compact a Time Machine backup history in .backupbundle format?

[rp92fl]

Hi to all,
I just got a more recent MacBook Pro than my current Late 2013 and in the transitory time in which I'll still have both but using only the newer one, I would like to keep the most recent part of the Time Machine history of the older one which went way back, occupying some 1TB of data. I've already trimmed 2/3 of the oldest snapshots (of the original ~40) with the tmutil deletecommand but the overall occupied space diminished by just about 250GB. I suspect there'd be some (or much) space to be claimed possibly.
I've read about the hdiutil command which has a specific compact subcommand for the purpose but this seems to work only with .sparsebundle Time Machine backups format and I can't find any alternative to be used with the .backupbundle format.
What am I missing? Is there any free alternative command or utility to do the job?
P.S. The MacBook Pro in question runs on Catalina

 

[gilby101]

If you started with 1TB and reduced it by 250GB, you are doing pretty well.

tmutil (when used correctly ) is the only safe way of modifying TM backups. I would not trust any other way. Don't even look for a free utility.

My advice it to stop messing with TM, keep the old backup safe, and start afresh on your new MBP.

 

[rp92fl]

Thanks for getting back.
Indeed I'm very suspicious myself too, but space in the NAS is a precious estate. I have a 1.4TB overall volume for TM Backups, and with the old MBPro keeping half for it having a 500GB SSD, the new one will soon suffer with its 1TB SSD.

I agree with you, no unknown or free utility on that. I was looking for something safe enough as the native macOS hdiutil command above. I'm surprised there's no equivalent alternative within macOS for .backupbundle backups as there was for .sparsebundle. Or shouldn't I?

 

[gilby101]

If you want to mess with it (and take a risk of losing it all), you could rename the .backupbundle to .sparsebundle and use the hdiutil command you have found. I don't think you will gain much.

Since it is a .backupbundle, you could copy that off the NAS and onto a modest USB HDD connected to the MBP. Check that it can still be opened (mounted) and files can be accessed. Delete it from your NAS.

 

[rp92fl]

Moving/copying the .backupbundle I've learned is something better to be avoided as it'll most probably break all the soft links between files and folders. I did it to free space on the TMBackup volume (moving the .backupbundle to another volume in the NAS) and it got corrupted. Luckily enough I've found a magical script that after a long crunching made it working again by repairing the structure and re-establishing the links.

Also, I've not dug into it yet, but is the difference between .backupbundle and .sparsebundle formats just the naming? Aren't they structure any different internally ?

 

[gilby101]

Also, I've not dug into it yet, but is the difference between .backupbundle and .sparsebundle formats just the naming? Aren't they structure any different internally ?

I think the .backupbundle has a few extra files at the top level, but otherwise the same. Look at the contents - they both have the same band structure.