delete redundant timemachine back up off an external hard drive

I'm not certain you can still delete a backup, even on the legacy HFS+ format drives. I don't have any HFS+ backups to try, but it seems from posts here that it is also not possible on HFS+ anymore.

The square brackets [] are not part of the command. That merely indicates an optional set of options.

I would try,

sudo tmutil delete -d /Volumes/10tb-backup/Backups.backupdb/iMac -t 2021-09-06-033201

or,

sudo tmutil delete -p /Volumes/10tb-backup/Backups.backupdb/iMac/2021-09-06-033201

Make sure you have given Terminal Full Disk Access in Privacy & Security System Preferences.

Can you explain what you mean be redundant? I would expect that to be a complete backup set, not one particular timestamp. I'm also not sure why you expect to gain by removing the one timestamp. Odds are it contains very little changed data, so you won't gain any appreciable storage space.

One can not " cherry pick " Time Machine Backup Snaps Shots for the Time Machine Backup drive.

The Utility has marked the Drive a Read Only and Only Time Machine has the ability to remove Old Snaps s=Shot with it deems more space is required for New Snap Shots.

1 - Get another External Drive and enable it in Time Machine Backup Utility

2 - Set aside the existing TM Backup drive in a Safe Place like Safety Deposit Box of Bank it in a Fire Proof Vault in you residence

3 - That drive can be kept of later usage and or Re-Purposed at a later time

4 - Or, Reformat the Existing Drive and start a New TM Backup Regime on that drive

Deleting Snap Shot created by TM Backup Utility on an existing drive, especially if the drive is in the APFS Drive format will have consequence.

It may corrupt the Index File used by TM Backup and in so doing, ALL the Snaps Shot would be Lost / Unusable

Deleting Snap Shot created by TM Backup Utility on an existing drive, especially if the drive is in the APFS Drive format will have consequence.

It may corrupt the Index File used by TM Backup and in so doing, ALL the Snaps Shot would be Lost / Unusable

It's obviously not an APFS Time Machine backup because there is a Backups.backupd folder.

arethusa1917 wrote:

Brilliant Barney, thank you, that works :)

By redundant, I mean I have been running on my new Mac Mini for months now and the old iMac backups go back three years. I'm happy taking the risk that they won't be needed. So I'm deleting all the iMac TM backups that are in a separate folder and not referenced by the new computer set up, see below.

I would just erase the drive and start over. However, it would be an APFS backup and there would be no way to do what you just did.

Good catch and missed that 😂

So what would be a good suggestion to OP question ?

P. Phillips wrote:

So what would be a good suggestion to OP question ?

Wait for it…

See it.

Thanks for pitching in here 😎

Welcome