Stalled transfers: large copies fail partway

[Tuesday, May 13th]

Users are reporting an in issue in which copying either large files (or sometimes large numbers of smaller files) from an external drive (USB or Firewire) fails with a hang. When this problem occurs, the target file may have a size of zero KB, indicating no data was transferred. This also occurs when FAT32 drives are attached to a Time Capsule device, causing the Time Capsule to crash and require manual restarting.

As described by Apple Discussions poster Greg Freeman

"I am trying to copy some large files my itunes music library 22G from an external mac formatted USB drive to my G5 and the process keeps stalling at various points , usually after a couple of gigs have been transferred. Clicking on the stop copy button does nothing and the only way to interrupt the failed copy is to relaunch the finder.The files were copied onto the disc from the same mac with no problems. "

The workaround for this problem involves ensuring that the drive is formatted to "Mac OS Extended", and not "FAT32". While drives formatted to FAT32 load and ostensibly work well with Mac OS X, there are apparently some problems with how OS X handles large files in this format. Most external drives that are advertised to work with both Windows and Mac are formatted to FAT32 (Drives may appear to be "Mac Formatted" but will in fact be FAT32); however, for best performance and compatibility it is recommended to reformat them to NTFS for windows usage, or HFS for Macintosh uses. The drawback to this is the loss of some native compatibility: Windows cannot read or write to HFS without third-party software, and OS X cannot write to NTFS but it can read it. 

If a user is using a Time Capsule device, then formatting to HFS should help the situation as the Time Capsule device will handle all the I/O for the drive and will allow Windows machines to write to the drive.

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