transfer big file to fat32 fs on android emmc

Summary: 

 - Fat32 doesn’t support file size more than 4GiB; 

 - No crashes during transferring big files to eMMC storage, 4.5GiB+ outsize; 2.5GiB+ OK in my test, using “cp” and “adb push”);

 - I had NO idea for MTP mode in Linux. (Any hints?)

$ dd if=/dev/zero of=test-file-4.5g bs=1024 count=4500000

-rw-r–r–   1 root root 4608000000 2011-09-29 12:43 test-file-4.5g

/dev/sdb              11915392       960  11914432   1% /media/8780-09E2

$ time cp test-file-4.5g /media/8780-09E2/

cp: writing `/media/8780-09E2/test-file-4.5g’: File too large

real    33m55.000s

user    0m0.050s

sys     0m12.500s

-rw-r–r– 1 root root 4294967295 2011-10-08 16:29 /media/8780-09E2/test-file-4.5g

$ /bin/rm -fr /media/8780-09E2/test-file-4.5g

$ time adb push /test-file-4.5g /mnt/sdcard/

failed to copy ‘test-file-4.5g’ to ‘/mnt/sdcard//test-file-4.5g’: File too large

real    14m24.386s

user    0m0.150s

sys     0m10.370s

$ time dd if=/dev/zero of=test-file-2.5g bs=1024 count=2500000

2500000+0 records in

2500000+0 records out

2560000000 bytes (2.6 GB) copied, 63.4219 s, 40.4 MB/s

real    1m3.554s

user    0m0.260s

sys     0m7.420s

$ cp test-file-2.5g /media/8780-09E2/test1

Disconnect phone memory card;

$ adb push test-file-2.5g /mnt/sdcard/test2

Mount phone memory card;

-rw-r–r– 1 root root 2560000000 2011-10-09 13:01 test1

-rw-r–r– 1 root root 2560000000 2011-10-09 04:00 test2

/dev/sdb on /media/8780-09E2 type vfat (rw,nosuid,nodev,uhelper=udisks,uid=0,gid=0,shortname=mixed,dmask=0077,utf8=1,showexec,flush)

Ref:

http://en.wikipedia.org/wiki/Fat32

Limits Max file size[1]      4 GB minus 1 byte