MacOS Sierra - 50-100GB of system storage??

dianeoforegon, you have the right idea.

listen everyone, i had this issue today 12/28/16 where i know i had 350Gb of free space and i was getting the system storage almost full message. I installed omnidisksweeper and i quickly saw there was a log file that was in my case associated with parallels that was 350Gb in size. I deleted the file and emptied the trash. problem solved.
as for what caused the log file to report at that size i'm not sure but I will continue to monitor.

I wonder if the files created where "backup files" created of your VM. I'll see if I can find info about what Parallels might store in System folder.

Not sure but what was odd is I haven't run my VM for a few weeks and I just had the error today. The file that was reporting the 330Gb or so was a single log file. Runaway process maybe?

Found out the following info regarding large files:

This can happen. Usually, it is a result of the user turning on “verbose logging” for a specific reason, and then not turning it off afterwards.

Also, to be really precise, the log files are stored in the Library folder, not the System Folder.

This is would be the more typical space usage:

In the future if you find files in your System folder, please take a screen shot. This would help identify the problem.

Command-Shift-3 takes the entire screen

Command-Shift-4 takes a portion of the screen. <--use this one

Click on the camera icon in the toolbar of the reply window to post. Select image to upload.

Be careful not to include any private information.

same, I only have 20gb of storage left now and it's a real big problem

For me it was the Adobe After Effects Media cache that took apparently about 50 GB of space.

err ... 10 times the storage is definitely not needed. I don't even want to know what a Macbook with a 1TB SSD costs ... very likely not worth.

I have just updated to OS/X 10.12.5 yesterday. Finder shows that I have 5GB more of free storage after the update. It looks like Apple is working hard in correcting the storage problem.

Hi Karl,

That does seem high. When you go through the about this Mac then do manage storage what are the items consuming most of the space?

Same here with a 13 Inch MBP from early 2015 with 128Gb SSD.

It reports 64Gig free, and says 105 Gig are taken by System.

I did this and it worked for me. Thanks.

Was it removing local Time Machine backups or using OmniDiskSweeper via the terminal?

Thanks for the feedback. 🙂

I have the same problem too. My new MacBook Pro with Touch Bar and Touch ID ... 512 GB SSD... barely a month old shows system storage of over 200 GB!!!

What is causing this and how can I reduce it?

Really enlightening answer, thx RoyalFlushAK(s) !