syncdefaultsd uploads huge amounts of data

Question

Level 1

16 points

syncdefaultsd uploads huge amounts of data

I have a problem that persist over a long time. System process syncdefaultsd is uploading huge amounts of data - approx. 1 GB per hour. When it starts, it runs about 15 minutes – and uploads usually about 500 MB of data. Then the process terminates. And after few minutes a new instance of the process is started and it uploads the data again. The exact amount of data deviates each time.

That would not be so surprising - this process is synchronizing data with iCloud. But the problem is that there are no data to be synchronized! In general – I am not using iCloud. I have 0 documents there. I have 20 Photos there. I only have the messages and IOS device backups there. So the synchronization batch should be in kilobytes - not even a single megabyte. (iOS backups have nothing to do with macOS – and disabling of Message synchronization has no impact on the amount of data transferred)

Further information:

According to Activity Monitor, the process syncdefaultsd hold the following files:

/Users/Martin/Library/SyncedPreferences/com.apple.kvs/com.apple.KeyValueService.EndToEndEncrypted-Production.sqlite

6

/Users/Martin/Library/SyncedPreferences/com.apple.kvs/com.apple.KeyValueService.EndToEndEncrypted-Production.sqlite-wal

7

/Users/Martin/Library/SyncedPreferences/com.apple.kvs/com.apple.KeyValueService.EndToEndEncrypted-Production.sqlite-shm

8

So I guess this process has something to do with End-to-end encrypted iCloud transfers – like the KeyChain (I do not use it either) – but as far as I know these transfers are not only about the KeyChain.

The files with this End-to-end encrypted database are small – they are all together about 4 MB size in my case so this does not explain the upload misery either.

Problem is clearly linked with my iCloud account. So – this is happening on all the machines with my iCloud accounts – and only my iCloud accounts are affected - other iCloud accounts on the same machine are fine.

Actually – this process behaves like perfect Spyware – uploading huge amount of data to Apple, zero control over it and I have no info what is it doing. It transfer much more data than what I have allowed macOS to share with Apple.

My questions are

- Anybody has an idea what’s going on – why it uploads a data? How to stop it?

- Is there any detailed logging of what this idiotic process is doing?

- Any idea of what king of data is passing through this database and/or service?

- Any idea how to re-initialize this End-to-End encrypted transfer database – not only locally, but also in iCloud.

(macOS Big Sur 11.3.1 - the current latest)

MacBook Pro Retina

Posted on May 17, 2021 1:05 PM

Reply

Answer 1

Best reply

Old Toad

Level 10

207,463 points

May 17, 2021 2:34 PM in response to MartinBeran

Have you booted into Safe Mode, Start up your Mac in safe mode - Apple Support, and see if the problem continues?

Also log into a basic admin user account, Set up users, guests, and groups on Mac, and see if the problem persists. This tells us if the problem is limited to your user account or is system wide.

Also have you tried killing the process from within Activity Monitor and see if if continues running at high CPU usage or not?

Have you installed or run any "cleaning", "optimizing", "speed-up" or anti-virus apps on your Mac?

Reply

Answer 2

MartinBeran Author

Level 1

16 points

May 18, 2021 1:51 PM in response to Old Toad

Well, most of the ideas proposed in your post are already addressed in my original post. There is no problem with CPU load, as long as syncdefaultsd is a system process it is started even in the safe mode. Problem is clearly linked to a single iCloud account (on all machines) and other accounts on the same machines are unaffected. I have no antivirus sw nor performance tuning sw installed.

I formulated some clear questions in my original post. Unless you have some clear answer please do not reply. Your response looks like copy-paste of general troubleshooting.

Reply

Answer 3

May 24, 2021 12:36 AM in response to MartinBeran

Hi it happen the same on my Mac mini M1 with latest Big Sur but not on my MacBookPro intel with Catalina (same icloud account), from some months. Less frequently one to three time a day randomly long transmission about 15 to 30 minutes with almost all my upload band.

I see clearly this with Little Snitch after some days gigabytes of data transmitted, no activity from me on icloud files (few stuff) that use other services to transmit files data. Also contacted Apple support, try to quit and reenter icloud account solved for some days more than a week, after a reboot syncdefaultsd restart to transmit data with same pattern. After this the amount of data transmitted is lower but growing day by day so seems something that It is not completed and accumulates over time.

Very annoying for me when it starts when I need bandwidth for work, unstoppable on M1/Big Sur. I thought it was a problem of M1 like sending log to Apple since I never found this problem on my previous Mac Intel (same account and iCloud). It is very ugly to me to see the Mac send lots of data without knowing what is inside!

Reply

syncdefaultsd uploads huge amounts of data

Similar questions