reducing used/increasing available space on hard drive

[Dervla]

Hello from a new member,

short version: why did’t the “Used" TB on the Macintosh HD decrease after I deleted 300GB of files?

long version:
I am preparing to replace my late 2015 27” iMac. It has storage of 2TB on the Macintosh HD and 121GB on Extra Internal Storage.

I will replace the 2015 iMac with an M4 24” iMac with 32GB memory and 2TB storage.

On the 2015 iMac, when I click on Applications > Utilities > Disk Utility, the Macintosh HD shows Used: 1.37TB and 632.7GB available.

I would like to reduced that used number/increase the available number.

So, from the Pictures folder, I deleted about 300GB of files from the Pictures folder, and emptied the Trash. I did the deletion after Time Machine backups and after copying about 260GB of RAW and about 40GB of other photographs from the 2015 iMac to an external hard drive.

Then I restarted and looked at the Used number, it has not changed. How come?

I thought the amount used would change from about 68% (1.37GB/2GB) to about 50% (1GB/2GB). It did not.

Any ideas?

Thank you

 

[Bigwaff]

Version of macOS installed?

 

[Dervla]

Monterey 12.7.6

 

[doogm]

I wonder if it's a Time Machine local snapshot? See https://support.apple.com/guide/mac-help/about-time-machine-local-snapshots-mh35933/mac

Try using Disk Utility to see if you have any snapshots and then see if you can delete them. See https://support.apple.com/guide/disk-utility/view-apfs-snapshots-dskuf82354dc/mac

 

[Dervla]

Hi,

Thank you for your reply. Are the items in the orange oval what I am looking for and should see if I can delete them?

 

[Bigwaff]

Hi,

Thank you for your reply. Are the items in the orange oval what I am looking for and should see if I can delete them?

If you have a recent TM backup, then you can delete these snapshots. Otherwise, perform a TM backup first.

 

[doogm]

I honestly think that if you run Time Machine to completion then the snapshots will go away and the space will be recovered.

I'd also think that if you have been running Time Machine over time then you already have those items backed up, so you could probably delete them if you absolutely need the space right now, but it's up to you.

 

[Dervla]

Hi doogm,

I am running Time Machine now. I use two external hard drives for the backups and with the 2015 iMac & the two LaCie portables the backups take a while. And yes, I have been using Time Machine over time. Not hourly all the time but usually several times a day.

After the backups finish I will look at Disk Utility to see if the snapshots are still present or gone. If the snapshots are still present 24 hours after the time of the most recent one I will see if I can delete them. I am thinking it may be better to start the M4 iMac with about 50% of storage used rather than about 68%. Does that seem like a good idea?

Thank you.

 

[Bigwaff]

I am thinking it may be better to start the M4 iMac with about 50% of storage used rather than about 68%. Does that seem like a good idea?

The TM snapshots won't be transferred to the M4 iMac when using Migration Assistant.

 

[gilby101]

Not hourly all the time but usually several times a day.

TM is happiest if you set for automatic hourly backups. Snapshots (called local snapshots) on the source will be deleted after 24 hours.

I am thinking it may be better to start the M4 iMac with about 50% of storage used rather than about 68%.

All depends how much you expect it to grow. I try and keep my internal drive (512GB) at about 60% and move the excess (photos, etc.) to another disk when usage gets above 75%.

 

[Dervla]

TM is happiest if you set for automatic hourly backups. Snapshots (called local snapshots) on the source will be deleted after 24 hours.

All depends how much you expect it to grow. I try and keep my internal drive (512GB) at about 60% and move the excess (photos, etc.) to another disk when usage gets above 75%.

thank you and thank you!

 

[Dervla]

Looks much better to me! What do you think?

I did not have to delete anything, the 300GB snapshots made on the December 21 disappeared on their own.

Thank you _very_ much for your help.

 

[doogm]

Right, that's Time Machine doing its magic. It saves the snapshots until it is able to offload them to the external Time Machine storage device and then is able to free the snapshots.

 

[gilby101]

Looks much better to me! What do you think?

As @doogm says, TM's magic. The 24 hour wait is what causes confusion.

It saves the snapshots until it is able to offload them to the external Time Machine storage device and then is able to free the snapshots.

That is not quite the sequence.

When TM starts a backup, it first creates a snapshot on the source volume - this becomes the source for the backup. TM then copies changes (since the previous snapshot) to the destination volume and creates a snapshot on the destination.

After a successful backup, TM does some tidy up of snapshots. TM removes all snapshots over 24 hours old from the source volume. TM also removes snapshots on the destination volume according to its thinning rules - keep 1 backup per hour for 24 hours, 1 backup per day for a month, 1 backup a week for anything older.

Snapshots are a frozen and consistent view of the volume's file system at a particular moment. As such they are suitable for disaster recovery.

 

[Dervla]

posted to macOS threads "reducing used/increasing available space on hard drive" and "macOS Extended (Journaled) or AFPS?”.


YES!

Did the migration. This post was sent from the new M4 24” iMac, with 32GB memory and 2TB storage, after the migration from the late 2015 27” iMac running Monterey 12.7.6, with 16GB memory and 2TB storage (about 1TB used) on the Macintosh HD and 121GB on Extra Internal Storage.

The Time Machine snapshots of the 300GB of files, which (the 300GB) I copied to external hard drives, deleted from the iMac’s hard drive, did a Time Machine backup, waited overnight, and did another Time Machine backup, disappeared on their own.

I used APFS to make a new Time Machine backup of the 2015 iMac and followed instructions for the migration to the 2024 iMac.

Time Machine is making automatic hourly backups of the M4.

Thank you to all who provided guidance.