• Samsung Galaxy S Relay
  • Android 4.4.4
  • Cyanogenmod 11

I've tried many different solutions to sync my phone's SD cards with a computer over Wi-Fi, leaving them to run overnight because there's so much data (~30 GB), but in the morning the phone is slow and unresponsive, warm to the touch, apps like Gentle Alarm don't work, etc. It becomes so slow that when I try to use it, it eventually stops responding completely and reboots itself. I've tried:

  • FolderSync
  • Syncthing
  • Samba on phone
  • FTP server on phone
  • SSHDroid on phone and SyncBack on computer
  • iDrive Backup

At first I assumed it was because the apps were flawed, so I tried different solutions, but since it happens with all of them, it seems it's a more fundamental OS problem, like accessing too many files at a time or sending too much data over the network causes the phone to become unstable? Maybe a memory leak or it opens files and never closes them or something? How can I diagnose this and make it workable? When I look at CPU/memory usage, it seems normal? (Though it reboots while I'm trying to check, so a CPU/memory usage logger would be better.)

  • Continuous data read and write in massive amount uses a good amount of CPU and greater the spikes in CPU the greater the heat it would generate. Try using a kernel or an app which can set the CPU at a specific (low or moderate) frequency. It would affect the read/write speed but overheating would remain under control. I've a related answer here: High CPU load during file copy to SD card
    – Firelord
    Feb 25, 2016 at 16:13
  • @Firelord Ok, but why would the phone continue to have problems after the sync has been stopped? I would guess that phones automatically throttle their CPU when they're overheating, but it probably depends on manufacturer?
    – endolith
    Feb 25, 2016 at 16:16
  • 1
    I know it's not related to the nightly build because it's been happening since before I started using the nightly build, as I said above. Thanks for arbitrarily closing my question because it had a particular word in it.
    – endolith
    Feb 26, 2016 at 0:24
  • 1
    There are some testings that I need to know if you're comfortable with it: does this happen if you don't use the apps at all? Have you tried syncing some files on internal storage and see if this occurs? I have a hunch it's a problem with syncing external storage to cloud. Also, are there many small files, or only some big files? How often you sync it?
    – Andrew T.
    Feb 26, 2016 at 3:34
  • 1
    I still don't have any conclusion (hardware is not my strength), but I think it might be related to SD card read speed, the device memory, or the network speed. Probably there's a bottleneck between reading the file while syncing, which make it fail, but due to retry policy, the app still tries to sync it (and probably memory leak due to it), overheating the WiFi/device... or the SD card "temporarily died" due to extensive read while the app syncs. Unfortunately I can only provide one theory, which based on my experience, but I can't certainly answer it.
    – Andrew T.
    Feb 26, 2016 at 17:27


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