Hello David, On Oct 28, 1:56 am, David Given <[EMAIL PROTECTED]> wrote: > > Hi Jason! Thanks a lot for the tip - it did help. On other hand - I'm > > stuck. I was hoping to use sd card as a medium to transfer data > > between android app and usb host, but as it looks I can write either > > externally or internally but not both at the same time. I guess > > android developers had chosen not to implement fs synchronization, > > thus disabling concurrent writes. > > No phones can do this --- it's a filesystem limitation; FAT simply can't > cope with more than one concurrent user. Only really specialised > filesystems can do that, and most of them require additional hardware to > synchronise the different users. Thats not exactly true. FAT32 can do handle multiple concurrent readers/writes and that what it does all the time when you have fat- formatter partition on any modern multitasking OS. What is indeed correct, that no more than one FAT32 (and most others) filesystem can access underlaying storage simultaneously. What I don't sure, is how mass storage driver is implemented on android - if it uses hight level access via fs driver, there shouldn't be any problem writing both from external and internal processes as from fs driver's point of view those are just two local writers (somewhat similar to how NTFS server shares underlying single-user filesystem). On other hand, if mass storage driver shares a low-level storage access, and fs driver running on client side, there of course would be impossible to access local fs at the same time.
> If you want to allow the PC and the phone to access the device > concurrently, you'll need to use a file system server on the phone and > proxy requests from the PC. JCIFS looks helpful here. I would be happy if I just had an access to USB from android app (the whole fs thing is just a workaround) but AFAIK I unfortunately don't. And without way to physically transfer data, FS server won't help me much. Best Regards, Zigmar --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
