Help Link2SD problem: When app and its files are on external sd, things don't work.

[cutedroid]

My Samsung Galaxy Tab 4 has only about 12 GB free, and it's not enough for me. So I have a 64GB external microSD. I use Link2SD and the key, Link2SD Plus, to put apps and all their stuff (cache, data, etc.) onto my microSD.

Recently, I've been having problems with some apps. I can't download new data (like in Pocket, Amazon Kindle), or apps don't open up articles (like Wikipedia Offline). I'm pretty sure the problem has to do with Link2SD because when I move the app and its files (Data, Cache, etc) from the external microSD back onto my tablet's internal storage, the problem is gone.

Can anyone please help me diagnose. I can send you system logs or error logs.

 

[Hadron]

What if you leave the app data on device and just move apk & dalvik?

Back when I (briefly) used Link2SD I never had a problem, but I also never moved data to SD.

 

[cutedroid]

Hadron, thank you for your reply.
With the Pocket app, 100% of the files (cache, data, obb, etc) was on my microSD (2nd partition). Articles wouldn't be saved offline.

But by just moving "Ext. Data" back to my tablet's internal storage, articles were now being saved on my tab for offline reading.

 

[cutedroid]

What if you leave the app data on device and just move apk & dalvik?

But I don't want to. I want all, especially the bulk (i.e. data) to be on SD.

 

[Hadron]

I assume that the second partition is extfs (ext2, ext3 or ext4)? I don't think moving data will work at all unless you do that though. I've seen a lot of problems with partitions made using MiniTool, but those have usually been "doesn't work at all" rather than "works but the app can't save data", so it's probably not that.

Is it possible that Link2SD has set the file permissions up wrongly on the sd partition (so the app can't write to the data files there)? But I'd expect app crashes in that case.

In short, I don't actually know - as stated, moving data never appealed to me. It might be that someone with experience of this will show up.

If all else fails it might be worth seeing whether FolderMount can help?

 

[cutedroid]

I assume that the second partition is extfs (ext2, ext3 or ext4)? I don't think moving data will work at all unless you do that though.

Hi, Hadron. Yes, the 2nd partition is ext2.

I've seen a lot of problems with partitions made using MiniTool, but those have usually been "doesn't work at all" rather than "works but the app can't save data", so it's probably not that.

It's been a while since I set up the 2 partitions on my microSD card, and I can't remember exactly what I used. But I don't think I used MiniTool. I either used aParted on the Android, or gparted on my Linux laptop.

Is it possible that Link2SD has set the file permissions up wrongly on the sd partition (so the app can't write to the data files there)? But I'd expect app crashes in that case.

Hmmm.... how can I check file permissions?

Some times I have app crashes, but that's with other apps, like Google Docs and Google Sheets and Google Drive.

In short, I don't actually know - as stated, moving data never appealed to me.

Moving data doesn't appeal to me too; I wouldn't do it if I had a one-terabyte internal storage.

It might be that someone with experience of this will show up.

I do hope so.

 

[argedion]

I used Link2sd in the past and like Hadron never really used it to move data. From memory though when ever I was using Link2sd and I downloaded a new app the app actually downloaded to the /data/app folder and then would be moved by Link2sd after the download was complete. Not sure if it still works that way or not. I think the big issue your having though is that most apps are trying to download their data to the /data/data folder and if the folder has been moved to an sdcard then the app not Link2sd has issues working. /data is its own partition. So when you move the apps and data to another partition that isn't /data apps don't know where to store their information and Link2SD can't grab it to move it to the desired location. At least that is what I believe to be happening here. Again though never used it to move data but I always understood data was in its own partition.

 

[cutedroid]

I used Link2sd in the past and like Hadron never really used it to move data. From memory though when ever I was using Link2sd and I downloaded a new app the app actually downloaded to the /data/app folder and then would be moved by Link2sd after the download was complete. Not sure if it still works that way or not.

Thank you for your post, argedion. There is an option for Link2SD to move a new app to external storage after a new app is installed.

I think the big issue your having though is that most apps are trying to download their data to the /data/data folder and if the folder has been moved to an sdcard then the app not Link2sd has issues working. /data is its own partition. So when you move the apps and data to another partition that isn't /data apps don't know where to store their information and Link2SD can't grab it to move it to the desired location. At least that is what I believe to be happening here. Again though never used it to move data but I always understood data was in its own partition.

I have not manually moved folders from internal storage to external storage (i.e. microSD). I believe the way that Link2SD works is that folders on the internal device are kept there, but Link2SD moves app data to the external SD while fooling Android in thinking that the app data is still where it originally was (i.e. on the internal storage).