Yeah I have the exact same problem as you. Except that I have only a 128 GB SSD so this is MUCH more of a problem for me. I'm running the first public beta of 10.13, and System for me is taking 115 GB. My thinking now is to update to the 2nd public beta, but because I have no storage space left, I can't download the update. I have already removed pretty much every single file I can in order to make space for this 2nd public beta update, but every file I remove doesn't free up storage space. The used space just seems to stick there no matter what I do. I'm really at a loss of what to do at the moment. Any suggestions??
The biggest problem for me is that I can't restore my MacBook Pro back to 10.12 with Time Machine/Migration Assitant because of a problem/bug with time machine that started when I updated to the first public beta. Basically, time machine backups will not start for me at all, no matter what I've done. Someone told me that Apple intentionally (temporarily) disabled time machine on the first public beta. I'd rather not have to restore my Mac if I don't have to, ESPECIALLY if I don't have a time machine backup of it right now that I can always come back to if I need.
Explaining everything that I have tried again in this post would be kind of a waste of time, so just check out the links below to see more details about what's going on and what I've already tried. As I was scrolling throught these posts, I noticed a couple suggestions about verifying the TM backups via the option key and the TM menu bar icon, and running fsck_apfs on single user mode. As for the verify backups option, when I hold down the option key and click on the TM menu bar icon, the Verify Backups button is greyed out, which I think is because I use a Seagate USB external drive for time machine rather than a network apple-made time capsule. Is that true or no?
2 posts above mine (nick101's post on July 12, 2017 at 8:35 am) - I am willing to try that one, but only if I can make a time machine backup right now first.
In case your interested, or if anyone has any suggestions on how to solve my 2 problems, here are links to developer discussion questions I posted.
Time Machine backups fail - https://forums.developer.apple.com/thread/82024
I have no storage space left due to System taking 115 GB - https://forums.developer.apple.com/message/244774#244774
Here's a couple more things I thought I should mention about what I DID NOT TRY YET.
- Resetting the NVRAM
- Re indexing spotlight
- fsck_apfs in single user mode
- deleting /.MobileBackups using Finder or Terminal
- Booting into safe mode
- Running first aid from recovery mode
Note that I DID try RUNNING FIRST AID from disk utility ON MY NORMAL USER ACCOUNT.
I've kinda concluded that most of my problems should be solved in the next beta update, but I can't update to that new beta because I don't have enough storage space to do so. One more thing - /.MobileBackups is taking up 11 GB. Would running "sudo rm -rf /.MobileBackups" in Terminal work to remove those local TM backups (they are from mid-June). Like would doing sudo rm forcefully remove those files and recover drive space, or will it just do nothing to recover drive space like every other file I tried deleting/moving. also would that command hurt macOS or time machine in any way, shape, or form?
I don't mean to advertise, but if anyone has any suggestions whatsoever on how to help me with this storage problem or the time machine bug, please respond to this post or to my 2 posts linked above. Any help is much appreciated. Thx everyone!!