Trim or garbage collection

[Photogdave]

When does MacOs do its “garbage collection” or “trim”
I know with 3rd party SSD, they would do it automatically when the SSD was in an unused state.
I believe Samsung told me once if you boot Macbook in to recovery it would start while it sat or just let it sit 6-8hrs unused.
Just curious when the OEM SSD did this. I deleted a ton of files tonight and in the “about Mac” section is shows the increased storage now, but under disk utility it still shows the low available amount I had before.
I was thinking this was because it hasn’t yet technically “free’d up” the deleted blocks yet???
Will disk utility eventually match the storage info in “about Mac”

 

[chscag]

You probably need to reboot in order to obtain the correct amount of disk space remaining with Disk Utility. As for TRIM working, I believe it's ongoing as files are removed. But it does take a small amount of time before it shows.

 

[Photogdave]

You probably need to reboot in order to obtain the correct amount of disk space remaining with Disk Utility. As for TRIM working, I believe it's ongoing as files are removed. But it does take a small amount of time before it shows.

I did. Still didn’t change. I let it sit idle for a couple hours to see if it changes
[automerge]1571535634[/automerge]

 

[Photogdave]

Just as an update. I ran a disk speed check and noticed it was a good but lower on write speed than it was new.
I ran clean my Mac and purged the “purgeable” space. Re-ran disk speed and it went from a write speed of 500 to 1500!!!!
So for those that think it doesn’t matter, it does matter if you’re rendering large files as I do as a photographer.

 

[chrfr]

When does MacOs do its “garbage collection” or “trim”
I know with 3rd party SSD, they would do it automatically when the SSD was in an unused state.
I believe Samsung told me once if you boot Macbook in to recovery it would start while it sat or just let it sit 6-8hrs unused.
Just curious when the OEM SSD did this. I deleted a ton of files tonight and in the “about Mac” section is shows the increased storage now, but under disk utility it still shows the low available amount I had before.
I was thinking this was because it hasn’t yet technically “free’d up” the deleted blocks yet???
Will disk utility eventually match the storage info in “about Mac”

Trim and garbage collection have no relationship to the free space your computer shows.

 

[Photogdave]

Trim and garbage collection have no relationship to the free space your computer shows.

trim and garbage collection is same thing. Garbage collection is what Samsung calls there way of trim.
But I was hoping once the “garbage collection” was done, the purgeable space would be free and I would truly have my space back. All I know is, the purgeable space was definitely affecting my disk performance

 

[chrfr]

trim and garbage collection is same thing. Garbage collection is what Samsung calls there way of trim.
But I was hoping once the “garbage collection” was done, the purgeable space would be free and I would truly have my space back. All I know is, the purgeable space was definitely affecting my disk performance

Trim and garbage collection are not the same thing.
Regardless, they only work on the free space on a disk, and they happen at a level below the filesystem. You will never see free space change as a result of either trim or garbage collection operations.
Here's a good link for you to read: https://cindori.org/trim-vs-garbage-collection/

 

[motrek]

I had a purgeable space problem myself a few weeks ago. Laptop drive is 128GB. I couldn't download an update to XCode because it said it was out of space. Getting info on the drive said that it had 50GB free but 40GB was purgeable, i.e., it only had 10GB free until the purgeable stuff got purged. I had to find and run some Terminal script to purge the purgeable space. Who knows what was taking up that space. It's bulls**t that MacOS can't automatically delete this stuff correctly.

 

[Brian33]

For most people with large amounts of purgeable space, it is very likely made up of Time Machine "local snapshots." These are supposed to be automaticaly thinned (deleted) to free up more storage whenever it's needed, but it appears there are bugs or problems with this process for a bunch of people. I haven't found authoritative info about when or how these snapshots are (supposedly) automatically deleted.

Here's an Apple page that describes local snapshots and how to delete them yourself by turning off Time Machine temporarily:

https://support.apple.com/en-us/HT204015

One could also use the 'tmutil thinlocalsnapshots' command, but the above procedure is probably easier.