site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com Hi all, I'm seeing a weird error from pread in the following setup: The copy is done in DKIOCGETMAXBLOCKCOUNTREAD chunks (128KB for ATA). Mac OS X 10.5.7 (Darwin 9.7) on Intel. Hey Brian, -Ed _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... This email sent to site_archiver@lists.apple.com On May 20, 2009, at 2:55 AM, Brian Bergstrand wrote: Copying from a 300GB PATA drive connected via USB to another 300GB ATA drive connected via Firewire using the raw char devices for each. After copying about 37GB of data, pread fails on the source USB drive with EACCES (13). According to the man page, this is not a valid error return (although the man page may be out of date). So where is the EACCES coming from? The IOKit block drivers? And what does it mean in this situation? Thanks for any help?_______________________________________________ Potentially strange question... have you tried retrying the failed read? Or retrying after deblocking it to something smaller? Even better would be to watch an ATA or USB bus trace of the failed read. I suspect your issue is originating in the USB bridge, or the USB stack talking to the USB bridge. I'd bet something odd is happening and its bubbling up as the EACCES return. Also, you didn't say the drive was dead after this happens, so I suspect it's something transient. I've seen this type of thing crop up from time to time with various USB access paths to optical devices. Scary as all get out. smime.p7s