Why did auto-sync start to upload that much? It's been a month now that the auto-sync option on my phone makes it upload 30 MB per day (in addition to my usual upload/download rate) and still download only a few hundreds of KB. It blew up my quota in only 10 days so I had to deactivate it. The only app that I installed at that time was the Google Doc app.

I recently reactivated the auto-sync and I unchecked the doc sync in: Settings &gt; Account &gt; my account, but I'm still uploading 10 spare MB per day. I only kept Gmail, contacts and calendar syncing (just as before).

My questions are:


Do you know what can cause this, why it changed without any visible reason ?
Are there third-party apps using the Android auto-sync option to enable/disable their own syncing process ?


Note:

I use 3GWatchDog Pro, and this spare MB are shown under "Android System" so it's not very helpful.

If relevant, my device is the Motorola DEFY
Background

There are several applications that use the auto-sync feature from Android to regularly update their contents. In fact, according to the Google documentation, you can configure synchronization options for any of your apps.

Auto-sync is used to allow applications to synchronize data on their own schedule. This can be disabled, and accessing each application, you can manually sync its data.

Take note that automatic data synchronization is disabled if Background data is unchecked.

Some examples of accounts that can be found here are Google; DropBox; Viper; Facebook.



Configure general sync settings

To access the list of accounts currently using auto-sync, thus enabling or disabling the auto-sync for each one, you need to:


Tap your device "home" button;
Tap "Settings";
Tap "Accounts &amp; Sync".

From here you can see your accounts using auto-sync, what define whether they are allowed to auto-sync or not:

 indicates that some or all of an account’s information is configured to sync automatically.

 indicates that none of an account’s information is configured to sync automatically.






Upload/Download

Depending on the accounts using auto-sync, they can send as well as receive data. As your account data grows, the data synchronization uses more KB to keep your information up to date on your device and on the host.

While synchronization doesn't transfer all the information back and forward, only transfer the "new stuff", since the last sync their may be a large amount of data to be updated on one side, thus causing a large transfer of data to take place.



References


Android OS: Accounts &amp; sync settings