SSD is full (91% used), so is very slow, but deleting 50GB of space has no effect (is just marked purgeable). How do I purge it?

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SSD is full (91% used), so is very slow, but deleting 50GB of space has no effect (is just marked purgeable). How do I purge it?

SDDs get slower as they get fuller. Over 50% full, and you start to get slow down. Above 90% full, and they are very slow. When I open a file or application, I have to wait longer than my old HD based laptop - it takes 10-20 seconds.

I have the 512 SSD. "df -k" shows:

Filesystem 1024-blocks Used Available Capacity iused ifree %iused Mounted on

/dev/disk1s1 488245284 438978644 46455604 91% xxx

NOTE: if I include the full output of df -k, it says "You have included content in your post that is not permitted". I had to deleted the numbers where I have put xxx. There is something very broken with the permitted text algorithm if it doesnt allow simple integers, with spaces in between.

I.e. the HD is 91% full, which is a disaster for performance, not to mention it will also wear out the SSD faster ( I have worn out an SSD in the past, I have several VMS, databases, many dev projects with millions of files which change on every build etc).

So I deleted 50GB of files, and emptied the waste basket. Then I waited for 10 minutes. Then I rebooted. I expected the disk used to drop to 80%. It did not change at all, but in "about this Mac" it shows:

106.53 GB available of 499.96GB.

The missing 50GB is not actually deleted, so is still causing my mac to run like a 20 year old 386 with a 5000k RPM HD. In terms of loading files.

How do I actually deleted the 50GB of deleted files, which are not deleted at all, and free up the critical space?

NOTE: I have turned off auto backup in time machine, when I found it it was making backups locally to the already full SSD, and I deleted all its local backups. So its not this taking the space.

MacBook Pro with Touch Bar

Posted on Oct 30, 2019 3:35 AM

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sfromgi Author

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107 points

Oct 30, 2019 1:07 PM in response to sfromgi

OK, I have had "backup automatically" switched off in time machine since I found out some months ago it was the cause of my HD being full and running slow. When I switched it off I deleted all the local backups, and assumed the problem would not come back.

When the SSD was becomming unusably slow again, I ran the blackmagic speed and found it was giving 500 write and 1000 read (should be double that).

The disk was 91% full, so I deleted 50GB of my needed files, and emptied the trash, rebooted the machine. but the drive was still 91% full, although Mac incorrectly reports it as there being 100GB free (i.e. the OS lies to you that it is 80% full).

I find that althught automatic backups is off, it still created a 50GB backup file. When I dleted this, finally the disk went to 80% full, and running blackmagic the read and write speeds more than doubled.

It seems Apple dont know that a 91% full SSD performs like an old HD, and they dont want to you be able to deleted your files to fix it, and they dont want you to be able to disable the crippling local backups. Of course they don't want you to be able to upgrade your SSD either, but at least they could let us manage what little we have.

So the fix is to regularly deleted your local backups, before they choke your HD. Use this command to list the backups:

$ sudo tmutil listlocalsnapshots /

And this command to delete them (supplyting the number part of the backup name as a parameter)

$ sudo tmutil deletelocalsnapshots

e.g.:

$ sudo tmutil deletelocalsnapshots 2018-03-01-002010

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SSD is full (91% used), so is very slow, but deleting 50GB of space has no effect (is just marked purgeable). How do I purge it?

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