On 2014-08-10, Marko Rauhamaa <ma...@pacujo.net> wrote: > Christian Gollwitzer <aurio...@gmx.de>: > >> Am 10.08.14 11:39, schrieb Steven D'Aprano: >>> Android phones don't mount as storage devices? >>> Oh well, that's Android crossed off my list. >> >> Not any longer. They used to, but the support for mass storage was >> dropped in favour of MTP > > I don't see anything inherently wrong with an open protocol like MTP. > >> to allow concurrent access from both the computer and the phone. > > I don't know MTP at all, but > > MTP allows no parallelism; unlike USB mass storage, MTP has been > built to only allow a single operation at a time (for example, read, > write or delete operation), while no other operation can be executed > until the previous operation is complete. > <URL: http://en.wikipedia.org/wiki/Media_Transfer_Protocol#Drawbacks>
That's the within MTP protocol itself, and that's not the "prallel access" problem which MTP was intended to address. What MTP allows is parallel access between the MTP protocol server in the phone and the rest of the phone (OS and apps). In order to mount a partition as a USB mass storage device, it has to first be unmounted by the Android system. That's OK for an SD card that doesn't contain anything important required by the Android system, but it means that you can't mount the "system" partition without shutting down the phone completely. For phones that don't have an SD card, there is nothing _but_ the system partition, and to mount it as a USB storage device you would have to completely shut down the phone. People don't like that. They want to keep the phone on while their doing <whatever> with their MP3 files and JPEG files and whatnot. The only practical way to do that is to define a file transfer protocol that doesn't require the entire parition be unmounted by the phone. Hence MTP. It's something Microsoft came up with, so it of course has their usual level of "broken-as-designed" about it, but in general it works fairly well. For Linux systems there's a user-space MTP filesystem implementation that has always worked fine for me. So in practice, it works just like as somewhat slow USB mass storage device. -- Grant Edwards grant.b.edwards Yow! Now I understand the at meaning of "THE MOD SQUAD"! gmail.com -- https://mail.python.org/mailman/listinfo/python-list