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

It is almost certainly the Time Machine local snapshots as explained in a post above.

You can use the instructions above if you want to clear them - or, better yet, connect your Time Machine backup drive and let the backup work.

Whatever you do, don't fall for any of these "cleaner" applications like "cleanmymac" - they are scams.

I suspect there are some issues with the way the Time Machine snapshots are being stored and removed.

You can delete all local snapshots using this command:

sudo tmutil thinLocalSnapshots / 10000000000 4

You might not see results immediately. Give it time to completely remove.

Check to see if you have connection logging enabled for Mac Mail. I did, and was able to track down over a year's worth of connection logging( basically it records in a text file the details of every time you connect to a mail server and download or send messages). I was using around 145GB in my system storage, but was able to get that down to 39GB after deleting those logs and turning logging off.

To check this, open Mac Mail. Go to Window > Connection Doctor. Once that window opens up, in the bottom right corner there should be a checkbox that says "Log Connection Activity" and a button that says "Show Logs."
Click the button, and it will take you to the folder. Unless you specifically need those for some reason, all of the log files can be deleted, and as I stated, doing so cleared up over 100GB of storage for me.

Hope this help

I found an app called Dr. Cleaner on the App Store and it discovered a Mail log folder that was 130GB in size! It was only log files, nothing more. I feel Apple should include this kind of cleanup functionality into their Storage Management app, there is no reason not to. It's silly that the System node is greyed out where I could see that the system took up 200+GB of space, but there are no options to help you reduce that in Storage Management. That is really weak from Apple in this day and age. Kudos to Dr. Cleaner and similar apps which are at least filling the void in this area. But they are still 3rd party apps and I'm sure I'm not alone in feeling uncomfortable having to use such apps which go through all my files. I'm on MacOS High Sierra.

Girshon Rutstein wrote:

OmniDiscSweeper and I found 522.5GB Private out of which 479GB was Bluetooth thousands of PocketLoggerBluetooth, how do I delete them?

Those logs are in /var/log/Bluetooth/

You should be able to delete the log files from there, but you will probably have to authenticate with an admin user.

This was actually so helpful. I found 3 files taking up 15-20 Gb a piece hiding in my system storage instead of applications. I thought the OS was just taking up an insane amount of space. The application was super easy and clear to use, told me exactly what was taking up storage and deleted it without any problems.

Hi petey2428,

I would use Disk Cartography. It's an app directly from the AppStore.

Disk Cartography - clever disk space analyzer on the Mac App Store

-Oliver

120 GB of SSD storage doesn't do the job. What you need is 10x that amount of storage and way more memory to have a working machine. Got a bigger HD or better get a new machine and couple hard drives connected outside of your little computer.

Just checked my iMac and the System folder is 7.84Gb, Library folder is 4.88Gb and Applications folder is 7.99Gb - that's a total of approximately 21Gb all under Macintosh HD.

With all my other stuff, music, photos, documents etc the total is only 100Gb, still have 400Gb available! - so would say your usage appears rather high. Only thought is the upgrade process sometimes moves files into a folder that it deems not compatible with the new system and secondly sometimes Finder does not always report usage accurately - you could try booting into Safe Mode (hold the shift down on restart) and then when that's done boot back normally and see if that recovers some lost disc space.

Where do you see how much storage is taken up by System?

I saw this reported on another forum.

Thanks guys, went and got DiskInventoryX and found out it was Xcode simulators taking all that space.

Personally, I like OmniDiskSweeper to find large files.

http://www.omnigroup.com/products/omnidisksweeper/

Did you figure this out? I have the same issue with my early-2015 Air. 100GB on system storage.

This discussion might be useful for a few ideas if you haven't already viewed - Why does the system use 150 GB of storage?

Hi petey2428,

I just checked mine and system takes 108 G of storage.

I guess it is because that Mac counts all the files with unknown extension as "system" (anyone please correct me if this is wrong).

I have these video game support files with extensions of ".001" ".002"..., and they won't be found under "system information".

In a word, I don't feel that there are some sort of problems with your system. You might want to check if you have these kind of supporting files, some of them might be taking much of your storage.

These are mine: