Cannot copy a large file; space available

copy/pasteerrorfile-transferssd

Trying to copy (drag and drop) an ISO file from SSD1/MacOS Extended to SSD2/FAT32 (two physically different and internal SATA drives):

  • ISO file size: 4.7 GB
  • Space available on SSD2 partition: 20 GB

Error message:

"The item "*.iso" can't be copied because it is too large for the
volume's format"

Tried to copy on a USB memory stick (10 GB available): same message.

From the command line:

cp /Users/me/file.iso /Volumes/Untitled/  
cp: /Volumes/Untitled/file.iso: File too large

Copying on the USB stick, same error but after trying for ten minutes (i.e. it thought the space was available, but it was not).

Everything works when coping a smaller file (40 MB).

What is wrong? I have the impression that the issue is not related to the space available on the destination drive, but to the size of the file being copied.

System details:

  • MacBook Pro 17" 2009
  • OSX El Capitan 10.11.6 (the latest one I can use)

Best Answer

FAT32 has a maximum size for any individual file: 4 GB.

You can split the file into <4 GB segments, copy to the FAT32 disk, then recombine them once you've copied them off the FAT32 disk to somewhere else.

# make 4 GB file segments
truncate -s 7.8G /path/to/file
split --bytes=3.9GB --numeric-suffixes /path/to/file /path/to/file.part
# copy to disk
cp /path/to/file.part* /Volumes/yourFATdisk/

# copy from disk
cp /Volumes/yourFATdisk/file.part* /path/to/
# combine segments
cat /path/to/file.part* > /path/to/file

Adapted from https://superuser.com/questions/440509/getting-around-the-fat32-4gb-file-size-limit

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