PSA: The proper way to delete or shrink iPhone System Data use on disk Hi, So you may all be aware of the “date trick” for triggering maintenanced (a system process on iOS responsible for cache deletion and management) on iOS to invalidate and expunge System Data (caches) from the disk. But, cache sometimes gets revalidated - as in System Data goes back to its original size - presumably because maintenanced doesn’t finish its process before users set the date back, or because there is a scheduled maintenance period triggered by this date change to expunge the data that isn’t triggered immediately (the change to storage after this maintenance period is shown in Storage settings but isn’t actually freed at this time). I have figured out a reliable way to prevent this, and to trigger maintenanced to immediately expunge all cache for good. As in, with this method, you can actually get iOS to immediately reduce System Data use on disk and to have it stay for good. Essentially, you need to set the date into the future, twice. Read notes below before you begin. Notes: Make sure you follow Step 3. Also, it’s actually not recommended you do this consistently, as caches increase the performance of apps and iOS in general. This should only be done when it spirals out of control. Also only do this if you see System Data above 25GB for best results. I also recommend deleting and reinstalling Instagram and Discord, if you use them, as they seem to be the mostly sneaky apps camouflaging cache into System Data. Check your current System Data use on iPhone Storage settings. Close all your apps. Critical: Set your iMessages to stay around forever on iMessage settings on iPhone to avoid having your iMessages deleted! Go to Settings > iMessage > Message History > Select ‘Forever’. This is important. Set your iPhone in Airplane Mode and turn Bluetooth and Wi-Fi off (this is to avoid anomalies with iCloud, Apple Watch and other apps). Change the date to 1 year into the future from the real date. Make sure you followed Step 3 before this step. Wait 60 seconds. Keep your phone awake. Check System Data use again. It should be much lower. If you don’t see a change, close Settings, relaunch and keep checking. Change the date to 3 months in the future from the real date (this is essentially 9 months in the past from the last setting). Wait 60 seconds. Keep your phone awake. Check System Data use again. It should be around the same or lower. Change date back to Automatic. Turn off Airplane Mode. You’re golden! It’s absolutely ridiculous this process is even necessary, Apple should get on board to fix the System Data woes. They have been an issue for many years now. https://www.apple.com/feedback/iphone/ Answer from talley89 on reddit.com