[LG Optimus L90] lfom:
Hello, everyone!

It seems that there are many misinformation about using an external micro SD as internal memory when installing any of the (great) Marshmallow ROMs available to L90, so I decided to create this thread from my experiments and leave it open for discussion.

What is it?

With Marshmallow you can use an external uSD as internal memory, what is great for L90 because it has 8GB of internal storage, with only around 4GB available for users.

How does it work?

It's a Marshmallow feature so it's built-in, no need of extra apps. It will format a uSD inserted in the L90 micro SD slot and use it as internal storage.

The uSD card will work from now on only on your phone, but you still can unmount, remove and replace it with other cards as needed. All contents from /sdcard will be moved from internal storage to the uSD, and all apps that allow native "App2SD" will be moved too (you can choose to move or not, if you don't you can move apps manually later). Not all apps can be moved, but you can "force move" ones that don't support native App2SD, but be aware that it may break things, like widgets, etc.

How do I use it?

There are two ways to enable adopted storage:

1. it will offer you the option to use a newly detected uSD as internal or storage, so you'll probably see a notification when you insert a new uSD on your phone, or right after installing any Marshmallow ROM;

2. Go to "Storage and USB" in Settings app, select your external card, tap the three dot menu and choose Settings, it will then open a page where you can Eject, Format (erase) or Format as internal option.

Either way you will be guide through the process of formatting your uSD as internal memory and moving your data. Obviously, your micro SD will be formatted (erased) so backup any important data first.

Advantages

The main advantage is that it will improve your internal storage a lot. Even if you use a 8GB uSD, because it will move everything from /sdcard folder to the uSD. Also, if an app is moved, then all its contents (data, obb, cache) will be stored in the new adopted storage.

Problems

From what I've tested, the only problems are that even a Class 10 uSD is slower than internal memory and not as reliable. So make sure you use a fast uSD (I'd say Class10 is the minimum) and a reliable one. Of course, if you use the uSD to move data between your phone and other devices then you probably will want to keep using it as external (aka Portable) memory.

Observations (may be updated later)

1. If you don't choose the option to move your apps when formatting the uSD you can do it manually later: go to Settings, Apps, pick the app you want to move and then click on Storage, you should see a page with a button to move the app (and app data). If you see "Force Change" then the app doesn't support moving to external storage natively, and doing it may break something;

2. All internal storage will be used only for apps and apps data when using adopted storage, everything else will be on your external uSD, what means /sdcard is now on your uSD. Also every app and app data moved to adopted storage will be on your external uSD too, so removing the card will make those apps unavailable as well as any data stored on /sdcard;

3. You will still be able to access all data using MTP (it will show only Internal Storage, as /sdcard is on your external uSD now) or using TWRP 3.0.0 or later (/sdcard data will be available on the /emmc folder using the built-in File Manager, or separately using MTP). MTP on TWRP was very slow for me when I tried to use it, so slow it's useless for files > 1GB, but maybe it's because I have used Android File Transfer on a Mac, your mileage my vary;

4. Sometimes the format process may abort and Android will show your uSD as "corrupted" (maybe it's the wrong word for it). Don't panic. If you want to test your SD, use it on a computer and do a full format using FAT format, it will test the card. Simply restar the process if you've tested or you know your card is OK. If it still says your card is slow, don't worry, it may work fast enough for you (again, I am talking about Class 10 or higher);

5. When a uSD is formatted as internal storage it won't be "readable" anymore on any other phone or computer (OK, maybe you can on a computer that can read f2fs and its contents, but not the usual and normal way);

6. Going back is complicated: probably you will need to use a computer and MTP to copy the data from /sdcard to it, uninstall or move the apps you want to keep back to internal memory and then format your uSD card again as external memory.

7. It seems that you can use one uSD to both adopted and portable storage, see the link bellow (not tested, read the other page linked too):

Sam Liddicott: Android 6 semi-adopted storage

http://blog.sam.liddicott.com/2016/02/android-6-semi-adopted-storage.html?m=1

Most things discussed here can be seen with pictures in this page from Motorola support website:

https://motorola-global-portal.custhelp.com/app/answers/prod_answer_detail/a_id/109134/p/1449,9582

Cheers and thank you all for the great info I got from this forum! :good: