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macmesser

macrumors 6502a
Original poster
Aug 13, 2012
921
198
Long Island, NY USA
I recently re-authorized (in iTunes) my 4,1 --> flashed 5,1 High Sierra CMP and noticed an alarming phenomenon. All had been well with the machine and things looked fine after the authorization but I soon noticed that free space on my boot SSD (a 500GB Mercury Extreme Pro from OWC) had shrunk very significantly during the course of a few hours afterwards. Free space had been around 50-60% but it went down to 25%. I do not have a lot of stuff from the music store in iTunes and when I actually tallied things up, it was not more than a few gigs worth of music. Ditto for other types of content. Files I create are mostly always stored on internal HDs when done, so this is a mystery. I also cleaned up my email newsletter subscription and deleted a fair amount of useless stuff but no dent on free space. To make matters worse, the free space continued to shrink over the next couple hours until I got a message from TechTool Pro that my disk usage limit of 85% I set had been exceeded and I now had 14% free space left. Now I'm down to 7%. Would be very grateful if someone could clue me in as to what the heck is happening. I picked up a 1TB drive on sale yesterday and am planning on cloning my boot drive to it and replacing. Wondering if there's anything I need to fix before doing so.
 

Petri Krohn

macrumors regular
Feb 15, 2019
114
124
Helsinki, Finland
MacOS is like Google and NSA, they like to store all your data locally and index it for searches with Spotlight. One memory hog is the macOS Mail program. It will load local copies of all the emails you have ever sent or received, even if you use Gmail and the IMAP protocol. The good thing is that these cached files are not saved by Time Machine.

I have seen a 128 GB Macbook Air start warning about a filled drive. Turned out the mail program was using 40 GB of drive space. This is not the way IMAP is supposed to work. The idea of the protocol is to store email in the cloud, on the mail server. I could not find a way to disable the caching, apart from not using macOS Mail.
 
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macmesser

macrumors 6502a
Original poster
Aug 13, 2012
921
198
Long Island, NY USA
Run GrandPerspective on your Mac to find out what’s eating up your disk space.

http://grandperspectiv.sourceforge.net/
Thanks for the link.
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MacOS is like Google and NSA, they like to store all your data locally and index it for searches with Spotlight. One memory hog is the macOS Mail program. It will load local copies of all the emails you have ever sent or received, even if you use Gmail and the IMAP protocol. The good thing is that these cached files are not saved by Time Machine.

I have seen a 128 GB Macbook Air start warning about a filled drive. Turned out the mail program was using 40 GB of drive space. This is not the way IMAP is supposed to work. The idea of the protocol is to store email in the cloud, on the mail server. I could not find a way to disable the caching, apart from not using macOS Mail.

Thanks for reply. I wondered if it might be mail as I have several business related accounts and one personal one which they all are redirected to. I guess I should disable Apple Mail for any GMail accounts and manage all Gmail accounts with chrome. Then I could delete the mail from those accounts before deleting the accounts.
 
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Soba

macrumors 6502
May 28, 2003
451
701
Rochester, NY
GrandPerspective helped me to find some gigantic log files and identify some other memory hog files.

I’m glad it helped. I’m curious where the logs came from, so keep an eye on things to make sure you don’t have a problematic, runaway program somewhere that keeps creating huge logs.
 

macmesser

macrumors 6502a
Original poster
Aug 13, 2012
921
198
Long Island, NY USA
MacOS is like Google and NSA, they like to store all your data locally and index it for searches with Spotlight. One memory hog is the macOS Mail program. It will load local copies of all the emails you have ever sent or received, even if you use Gmail and the IMAP protocol. The good thing is that these cached files are not saved by Time Machine.

I have seen a 128 GB Macbook Air start warning about a filled drive. Turned out the mail program was using 40 GB of drive space. This is not the way IMAP is supposed to work. The idea of the protocol is to store email in the cloud, on the mail server. I could not find a way to disable the caching, apart from not using macOS Mail.

I was able to clone my boot SSD and swap it in, so no worries about disk filling up. All seems OK but there is a new mystery. The used disk space on the old boot drive is over two times larger than the used disk space on its new and bigger clone! These numbers should be nearly equal.

The old drive's finder info indicates as below:
Capacity: 479.89 GB
Available: 49.78 GB (750 KB purgeable)
Used: 429,412,212,736 bytes (429.41 GB on disk)

The new boot SSD, which was cloned from the old one using CarbonCopy Cloner without error, has finder info below:
Capacity: 1TB
Available: 852.71 GB (1.36 GB purgeable)
Used: 146,819,063,808 bytes (146.82 GB on disk)

How can clone have greater used space?
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I’m glad it helped. I’m curious where the logs came from, so keep an eye on things to make sure you don’t have a problematic, runaway program somewhere that keeps creating huge logs.
I’m glad it helped. I’m curious where the logs came from, so keep an eye on things to make sure you don’t have a problematic, runaway program somewhere that keeps creating huge logs.

They come from TechTool Pro and some others. I have disabled disk protection features in TTP but that does not account for all of them.
 
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