Help App Problems With New SanDisk Card

[tgm1024]

Yes, you generally need to format the SD card. You can do that with a laptop or a desktop that has a card reader. There may be apps that allow you to format the SD card also, but I don't know. I've always just used my computer. You want to format it fat32.

EDIT: Much of my understanding of this is in flux.

Not if she's using 4.4+ (KitKat). If you believe the latest buzz on 4.4+ (I don't know if Lollipop solves this or not), KitKat brought with it a huge security requirement. It essentially needs to have the SD card in one of the linux blessed filesystems likely EXT3/4, but it's unclear for her phone which one precisely.

FAT32 simply does not allow the proper unix ownership and RWXRWXRWX style file permissions that KitKat tried to bring with it. It essentially boils down to an app needing to keep in charge of it's own folders, and disallowing anything else from altering it. This is a much safer paradigm, but completely puts a hammer to things-----it more or less works if the application completely originates writing from the beginning, but should you have an app use the card and then later upgrade to 4.4(etc.) then apps that have been moved over the SD card will be horrendously flaky because 4.4 will try to deal with permissions that simply aren't there in the FATvariant.

Using the phone's internal format will work *EXCEPT* that if there's any files there, AFAICT nothing happens but a bulk erase. This is completely maddening.

I've read speculation by clicking around that the multiple mount/unmount/mount/unmount (over and over again) problems that folks have been having may be related to this, and (somehow?) may be what's clobbering the cards at the lower level. I have no idea why this would be the case, because a mount doesn't do anything special that I can think of, so I'm not putting any faith in that one.

 

[Paul pinckston]

No, lollipop doesn't solve it, that's why I used the disable internal zip for my l70. Also it seems adopted storage on mm is somewhat lacking, only certain parts of apk/dex/lib etc will install to sd, so link2sd is still preferable in my opinion.

 

[Paul pinckston]

Most phones use ext4 as internal (or rarely f2fs), I wonder if formatting sd in the same format will allow full access?

 

[Gmash]

I've never had to format an SD card to work in any Android device.

 

[tgm1024]

There is definitely more going on here that I can't quite figure out. I've been hunting this down in a different thread. The API change in 4.4 causes a lot of trouble for data held around by apps prior to an update.

Also, there is some information out there regarding an "ext emulation wrapper" that allows Android to treat a FAT variant as if it has the ext permissions it needs (pretends to be an EXT). I'm a long time software engineer, but simply never for Android, so I'm tiptoeing around the API's carefully on this one, and frankly I have no clue what's underneath it all yet.

There is a lot of flaky behavior that looks like a number of things with the advent of KitKat, and I'm digging into why right now and getting buried in filtering out innuendo from fact.

Before reading through the stackexchange sites, I started with these two:

KitKat SD cards --- What's Fixed, What's Broken, And What's Misunderstood

Pro Tip: Reclaim your SD card while using KitKat