I am wondering if I am missing something that has simply become a bit more 'hidden' in M. On my old phone, which had not reached Marshmallow yet, there were, say, a dozen apps that could move a portion of their code and data to the SD card, freeing up valuable internal storage. On a new phone (Moto G2, if it matters) that has gone straight to M, I am aware of the portable storage vs adopted thing now, and I have found the Migrate option... but when I do that, it says 'this will free up 1.X Mb'. Yes, you read that right - Mb, not Gb. Apparently it is moving pretty much nothing - yet this phone has more or less the same apps on it now (possibly a couple less, but there should definitely be at least 10 apps).

Is this a casualty of the changes in M? Why can I not move the same apps over as before? Or do they require getting the WRITE_EXTERNAL_STORAGE permission on the fly (i.e., must use them first to get it) before that is possible?

(While we're at it, why can't all apps be moved? It is my understanding that Linux / Android simply mount everything, regardless of source, as a partition - so in theory everything bar the most fundamental OS apps should be movable and usable without their code even realising they come from somewhere other than internal memory, surely?)

  • Welcome to Android Enthusiasts! 1) see our app2sd tag-wiki for explanations, and 2) our adoptable-storage tag-wiki. Also follow the relevant links from there, plus the "frequent" questions. Nothing new under the sun, all has already been asked before :)
    – Izzy
    Commented Aug 24, 2016 at 15:33
  • Ohhhh... wonderful, thank you for the links. So if I'm reading those right, now that I have let the phone adopt the entire 32 Gb card... I actually have 8 + 32 Gb available for all apps, and it will automatically install to the card when it runs out of space on the internal memory? I wish it would show it as one large lump so that I could tell it had worked! ;)
    – Jason Grey
    Commented Aug 25, 2016 at 16:49
  • That's the point I was never able to remember (what exactly happens to the "real internal storage"). I wouldn't use adoptable storage unless I'd really have to (and I cannot imagine a reason forcing me to that). For me (personally) the drawbacks are too high a price to pay.
    – Izzy
    Commented Aug 25, 2016 at 16:55
  • I admit I was not keen to 'commit' the card by adopting it, but since the card is not intended to be taken out (too fiddly to keep turning the phone off and take the back off, although I admit the Moto is by far the easiest to remove the cards of the phones I have had of late - credit for that) and was there purely to extend storage for apps (I am not a big media user (images / music / videos) ), if this actually works as I now believe, it is good for me :)
    – Jason Grey
    Commented Aug 25, 2016 at 17:03
  • sigh I went to migrate the data back to internal storage, now that I realise it wasn't doing what I thought, and now it has finally decided to move 1.1 Gb's worth of something onto the card - and it now shows 'Used 7.x Gb of 36.x Gb'. So I was worried about nothing! :)
    – Jason Grey
    Commented Aug 25, 2016 at 17:51

1 Answer 1


(Summarising into an answer as suggested by Izzy.)

When you adopt all or a partition of an SD card under Marshmallow (6.0) onwards, that SD card or partition becomes an extension of the internal memory. Depending on the phone model it may subsequently be referred to as internal memory, or it might still appear to be a completely separate entity. You can rename the card if you wish, to help clarify this.

Android will install / move apps and data (as older versions of the OS referred to the parts) onto the SD card portion as it sees fit, and thus when it runs out of room in the internal memory, it will happily go on to use the SD card.

When the internal memory or your card refers to 'Migrate data', this appears to be distinctly different from the data stored by any particular app, but instead appears to refer to that portion of the filing system that a connected device (PC or Mac) or a file manager app can view. Thus, there appears to be no value in using Migrate Data - just leave it where it is, the system will handle it.

(By way of demonstration, as per my original question using Migrate Data from the internal storage appeared to only move about 1 Mb of data; when I migrated it back, the system suddenly decided to move 1 Gb's worth of app and data onto the card, thus showing that it was indeed moving items around intelligently.)

  • > "and thus when it runs out of room in the internal memory, it will happily go on to use the SD card" Not sure about that. I have CM 13, Android 6 and no, no data is automagically moved to sd card when it runs out of room in the internal memory, neither before nor after migrate data.
    – sdlins
    Commented Sep 25, 2016 at 1:19
  • android is actually not happy to move apps to adopted sd card and reports out of memory instead, what i know so far, you should better connect sd card before before installing any apps, otherwise already installed apps will not use sd at all and android still needs space on internal storage to install apps Commented Oct 16, 2016 at 15:35

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