[Android Q&A, Help & Troubleshooting] pndwal:
Yes. Glad you found Adoptive Storage!

I used to use link2sd successfully, then switched to apps2sd which was vastly improved, and has inbuilt SD formatting tools and seamless script creation, as well as many more useful features, some of which are still useful for those using native adoptive storage (which uses F2FS, a faster file system than Ext4). Incidentally, it recognises and can format for native adoptive storage now too, but I never played with that.

I still used apps2sd till we had N, which utilises Adoptive SD Storage properly (unlike M), allowing most downloaded apps to be moved to SD (app developer dependant) in FULL, along with all user data. - No more need for link2sd or apps2sd when running out of space for apps. For me, this is one of the the best features of N for low memory devices like ours.

I'm including previously posted tips for Adoptive Storage use below. (It's time I revisited these and made a tidy list.):

Adoptive Tips:

-I Recommend fast SD card for phone-mem-like performance. I use 80MB/s SanDisk Ultra 64GB SDXC, but faster would be better.

-Dirty ROM updates (generally) retain all settings, so you don't need to save and restore adoptive storage encryption key in order to use SD data after dirty flash, but be aware that if anything happens to the stored encryption key, or you do a clean update or factory reset (eg because you can't get past password protection), all data on SD will be unrecoverable / lost for good (unless you save key to restore however, but this cannot be used on a different device. Key in data/misc/vold).

-Migrating data basically frees up phone memory to be used only for system apps, system data and unmoved apps (great for low memory devices).

-Moveable apps automatically go to SD (problems with this in M gone), but if app developer hasn't enabled 'move apps to SD' (they often forget to flag this, and apps will not then be moved), we can 'Force allow apps on external' in Developer Options in LOS and other custom ROMs (Makes any app eligible to be written to external storage, regardless of manifest values). This makes it the perfect out-of-the-box solution for a low memory phone!

-You can also go to Internal storage, Apps, and individually move any apps that have CHANGE button that haven't been moved already. Newly installed apps will be installed automatically on SD if developer supports SD installation.

-One movable app you should consider moving carefully (or move back to internal) is ES file Explorer if you use it's 'root explorer' - it loses root permission (fails unitial test) and won't allow root / system level access when on SD card. Other apps (especially those whose functions require root permission) may also suffer reduced functionality if left on SD.

-In a standard android file explorer (and with usb mtp computer connection) you will now see only your SD card, which is now your phone (user) memory (ie user data partition), and this has changed to the capacity of your SD card. It doesn't show up before migrating data, even though formatted as internal, as user data partition needs to be swapped to it from internal and the migrate data process does this. That's why there is no longer any internal phone memory showing. (It's now basically freed up for system apps, system data, and unmoved user apps.)

-Consistently, official TWRP (ie. twrp-3.2.3-0-y550.img etc) is the only one that can display Adoptive Storage, (I guess it correctly uses encryption key at data/misc/vold). L01 users can simply check they are using official TWRP if they cannot access files on SD from recovery after formatting SD as adoptive. L02 and L03 users will need to have unofficial twrp loaded to install ROM as all official TWRPs fail (with error 7) to flash any recent ROMs to their devices. To flash ROMs from SD, they will need to format SD as portable, or swap SD with another formatted as portable with installation files loaded. After ROM flash, they can swap to official twrp if they want to access phone data on adoptive SD in recovery. (Nb. Error 7 is only experienced updating ROM. Other files, GApps, Magisk, modem etc. flash fine from both official and unofficial TWRPs.)

Additional Tip:

-I still use Apps2SD at times to integrate system updates into system (using 'convert to system' module). [Unless you integrate them, updated system apps will be in internal (user), and original (deactivated) apps will be retained in system as installer can't alter system partition (also, system apps wont move to SD), so updating old GApps wastes space in internal. (Many updates will be installed to internal when first updating and more will be installed over time, leaving a deactivated app in system for each.)] Nb. I tried a stand-alone app (System cleaner 2) to integrate, but it messed up system apps. I went back to Apps2SD for this, and it integrated updates without problems. (Nb. Integrated updates and their data are often overwritten / messed up by new ROM installations, so you will likely need to reinstall GApps and repeat integration.)

-If you don't integrate regularly, installing latest GApps periodically can also minimise wasted internal space, restoring all GApps to system partition as they are flashed to it, and flash package also removes earlier GApp updates from internal (user), which is important for Y550 with its limited internal storage.

-Apps2SD has other functions that are still useful too, eg. Fix Device Lag (Trim partitions), etc. PW