iOS System Data usage keeps increasing

TidBITS Talk
1

I’ve been having a problem with excessive System Data consumption on my iPhone (iPhone 15 Pro, with 512GB, running iOS 26.5.2 at the moment). It seems to chew up ~1-2 GB a day, and rarely gives any of it up.

Background

The problem surfaced while I was traveling, when my phone reported it was running out of space. I checked iPhone Storage, and it showed under ~2GB remaining (if I recall correctly), with ~150GB used by System Data. (Symptoms started appearing, including loss of my calendar and contacts.) As a first step, I turned on Optimize Photos, which returned the ~77GB I had been storing locally (and also allowed my Calendar and Contacts to return). That got me up and running, but then the recovered storage started getting consumed again (about 2-10GB a day in this case), eventually reaching over 200GB.

As a side note, I was checking the remaining space each morning when I woke up, and noticed that the phone felt warmer than normal; perhaps there was some rogue process that was the culprit?

In any case, a web search led me to a recommendation to reset and restore the phone from a backup. I was unwilling to try this while traveling, so managed to limp along until I returned, at which point I did a full reset and restore (with some help from the local Apple Store). This appeared to solve the issue, showing ~30GB used by System Data, and ~180 GB free.

Since I did this, I’ve been tracking the System Data usage daily, and am finding that it is increasing by ~1-2GB a day. I’m now up to ~50GB of System Data, with ~160GB free. I’m now concerned that the problem has returned, but am not sure (1) if this number is within an expected range, and (2) what to do about it if not.

Question

Is there anything I can do to figure out what is causing this issue, or is it within normal operating parameters? The folks at the Apple Store told me they have no visibility into this at the process level, and the only thing they recommended was to do a full factory reset and set up the phone as new (i.e. *not* restore my non-default installed apps), then add my apps manually as needed. This feels like a severe solution, undoing the benefits of migrating from phone to phone over years of upgrade cycles, and I am not confident this would get to the root of the issue.

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Ah, an issue near and dear. I have a 128G iPad Pro. Few weeks back I saw close to 60G taken by the OS and system data. Just checked, over 40G now. I had gone asking about this and almost universally I got back was to wipe & restore. Which you’ve already done. I would never really attempt the “solution they gave you, it would be next to impossible especially if you have been using the device for years.

I’ve more breathing room on my phone (256G). It now shows 23G for the OS but only 1G for system data. Gotta say I am a bit surprised no developer has created some software to deletes that cached data.

Oh, both are running on the latest iOS 26.5.2.

3

System Data increasing at 1-2 GB per day feels very wrong to me. On my iPhone 17, running iOS 26.5.2, System Data is just 4.95 GB. I haven’t tracked it over time, but it’s certainly not increasing like yours.

The erase and restore dance is the only way I know of to recover that space, and as much as I hate to say, setting it up from scratch may be the only actual solution. But it might not work, as you suggest.

The only other thing I can think to suggest is to look at apps like video streaming apps that might create a lot of cached data. Do you have any usage patterns that would cause significant quantities of data to be downloaded and possibly cached?

4

Thanks for chiming in, Adam. I was kinda prepared for your response; if there was a better solution available, I would have expected to find it described somewhere “in the wild.” Since doing the erase/restore, I have user a few streaming apps (YouTube, Xfinity streamer, maybe one other), and maybe the News app’s Automatic Downloads feature is a suspect, but assumed those apps would manage their own memory (reflected in each app’s memory usage), not rely on shared cache. If that assumption is incorrect, then it would give me a possible troubleshooting clue.

This is the first time I’ve had this problem, but was an iOS update holdout, and only updated to iOS 26 a few months ago (from iOS 18). I suspect the problem began at that time, but can’t be sure. For now, I guess I can limp along at losing ~1GB a day or less until the next major OS update, hoping that will help.

5

Well, that was interesting. Adam, you got me thinking, so I went ahead and deleted one of my streaming apps (Xfinity Stream), and immediately recovered ~9GB of System Memory. So that app sure seems to be misbehaving. I’ll give it a day to see if the slow drip of increasing System Memory is stopped.

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6

One option is to back up the iPhone to a Mac (not iCloud) then do a reset and restore from that backup. Hopefully backups do not save cached data and other temporary files. But I have not tried this myself. Maybe others can confirm if this works?

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Is there reason to believe that a backup/restore from a Mac vs. iCloud produces a different result as far as cached/temporary files are concerned? I did not think that an iCloud backup restored such files (why would it?), but I don’t have special knowledge regarding this point. That said, I’m willing to try it if the problem persists (and if my experiment re: deleting a particular streaming app turns out to be a mirage).

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Not sure about differences between iCloud and local backups with caches and system junk. In the old days (!) iCloud backups were not as comprehensive as local backups. I use them for 2 main reasons
1 They are much faster - we haverelatively slow internet in Australia
2. I don’t always have access to the internet (currently a major internet outage in Australia)

Oh, and 3 I can easily use a local backup to migrate to a new phone, if the old one dies

A negative is that local iOS device backups can only be stored on the Mac’s internal disk. These days an iPhone backup can quickly use up available Mac storage. This is a major irritation which Apple doesn’t seem to care about. I keep an old iMac with a large hard disk going partly for these backups.

9

Still true, I believe. Certainly, my iMazing backups include iCloud data like Notes and Photos.

Agree with it being a major irritation. Suggestions:

  1. You may be able to create a folder on another disk and symlink the backup folder to it. Can be tricky. I have not tried for iPhone backups, but it may work.

  2. iMazing allows you to backup wherever you wish - works well. And it maintains a history which iCloud backups do not. At a cost, of course!

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Ah, thanks for the clarification. In my case, space and speed are not an issue for my backups, and furthermore I want my backups to explicitly not include things like cached and temporary files (which I believe would only restore the conditions for the problem I’m trying to solve). In my troubleshooting efforts, I just want to restore the prior state of my phone while omitting the temporary files that have ballooned. In other words, I want the leanest backup possible, not the kinds of backups that, presumably, utilities like iMazing can create.

As I reported earlier, the initial reset/restore that I performed did clear out the excess System Data, but then some process started filling it up again. I don’t think restoring a more comprehensive backup would have helped in my case.

11

It certainly sounds like a system process is producing excessive logging.

As much as I hate to say it, erase and restore.

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Yup, I had already done that, and the problem seems to have returned (though less severe than the prior time). Unless/until it gets addressed in a future update, perhaps a periodic erase/restore is in my future :weary_face:

13

Update with some odd observations today:

  • Morning check showed a slight increase in System Data usage (+2GB, to 52GB), then about 15 minutes later usage dropped to ~1GB, without any explicit action taken. (Perhaps the memory taken by the app I deleted yesterday–Xfinity Stream–finally was released?) Oddly, System Data dropped by 50GB, but available data increased by 70GB! (Where did the other 20GB come from?)
  • About 2 hours later, System Data jumped back to 54GB, after using the phone normally (and without any memory-hungry app usage, as far as can tell). So I seem to be back where I started, when I deleted the Xfinity app. (I was hoping this experiment identified the app as a suspect, but now I’m not sure.)

I’ll continue to monitor this over the next few days, but for now it remains a mystery.

14

One more update today: System Data dropped to ~1GB, then spiked back to ~56GB less than 30 minutes later under normal use. Is this the new normal under iOS 26? At this point I’m resigned to living with the issue, hoping for some resolution with the iOS 27 update.

15

What I’d try at this point is another erase and restore to reset system data. And then try to use as few apps as possible, checking before and after each, and probably once per day at the same time. I think you need more data to identify the culprit.

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16

Thanks for your advice; sounds like something to try while waiting for the iOS 27 update if the current behavior spirals out of control again.

What I’ve started doing for now is offloading apps that I think I’ve used since my last (relatively recent) reset/restore, and seeing if it makes a difference. Not sure if I’m fooling myself by believing offloading affects system data. I will also try deleting individual suspect apps next (since my experiment with the Xfinity Stream app demonstrated some immediate and significant reduction in System Data).

17

This may sound like a weird thing to try, but see what this does:

  1. Put your phone in airplane mode.
  2. Go into settings / general / date & time, turn off automatic date, and then manually change the date to next year.
  3. Don’t open anything else and put the phone down for 10-15 minutes.
  4. Change the date back to today and then turn off airplane mode and see if any storage has been recovered.

Explanation: as I think most OSes do, iOS deletes log files older than a certain date, so setting the date ahead temporarily will make the phone delete what it thinks are year-old log files. And if it does significantly reduce storage space, it will tell you that something is filling log files.

I’ll also note that I may agree with the Apple suggestion to factory reset and rebuild from scratch at this point.

Another thing to try is to delete all third-party apps and then reinstall them.

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18

I’ve seen this suggestion re: playing with the date/time to force a data purge, but felt nervous about unintended consequences (e.g. messing with data that relies on accurate time information). But maybe I’ll give it a try, since my phone has now returned to eating up 2-5GB/day again.

Can it really be log files that are causing this? Can’t imagine any app generating that much log data on a daily basis. I really wish there was a way to see where this data was being generated in the first place (let alone a way to just reset caches, etc.). The thought of rebuilding my phone from scratch (vs. restoring from a backup), after years of tweaking and configuring, fills me with dread…

19

iMazing might be able to show you log files on your device.

1 Like
20

I found a very interesting and relevant thread on MacRumors:

System Data Overflow Bug - storage full with 170GB of undeletable data! | MacRumors

This identifies a possible cause for the ballooning System Data problem: an icon redraw bug (where app icons and app folders appear to redraw from time to time), which correlates to a jump in System Data usage. It appears that the icon cache keeps growing, without clearing old icon data. It may be related to the number of apps installed (in folders or individually), of which I have hundreds.

I’m encouraged by the effort in that thread, in that this isn’t an isolated incident, and will possibly be addressed in the next major iOS update.

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