External Hard Drive Error Code: -50

[arsradu]

Set Mac OSX settings to put HD to sleep

I know it sounds backwards but to work around this error you'll want to go into System Preferences->Energy Saver and for both Battery and Power Adapter tick the box next to "Put the hard disk(s) to sleep when possible". Yes that means the OS will put all of your drives to sleep when it can but that's the only way I've found to fix the problem.

This fixed it for me. Thank you!

 

[Sedagah]

Set Mac OSX settings to put HD to sleep

I know it sounds backwards but to work around this error you'll want to go into System Preferences->Energy Saver and for both Battery and Power Adapter tick the box next to "Put the hard disk(s) to sleep when possible". Yes that means the OS will put all of your drives to sleep when it can but that's the only way I've found to fix the problem.

What seems to happen is that some external drives have firmware which detects inactivity and spins the drives down. If OSX is not configured with the energy saver setting mentioned above then OSX is not expecting the drives to go to sleep. When accessing the drive after it puts itself to sleep obviously something gets messed up and the error -50 is thrown among other problems.

By configuring the OS to put disks to sleep the OS will issue spin-up commands. This totally resolved my -50 errors.

My reproduction scenario: Without the energy saver setting enabled after 5 minutes of inactivity my LaCie P'9231 external USB 2.0 2TB drive would spin down. Accessing drive via finder and trying to create a new directory or perform any write action would reproduce the -50 error. Drive would not eject properly and had to force eject. After the force eject unplugging the usb cord from my MacBook Pro (running Lion 10.7.2) and plugging it back in restored the drive's normal operation.

Troubleshooting Performed: Downloaded latest LaCie Firmware updater and updated firmware on external drive. This updated firmware allowed the OS to control the spin-up/spin-down (but does not disable the ability for the drive to put itself to sleep after 5minutes). This update also disabled the "EcoMode" settings within the "LaCie Desktop Manager" software. With this update the repro scenario above continued to reproduce the error -50 failure.

I ran DiskUtility and noticed that although I had reformatted the drive to "Mac OS Extended (Journaled)" I had not set the partition scheme. It was still set to the older "Apple Partition Map". I set this to "GUID Partition Table" and reformatted (one 2TB partition). With this change the repro scenario continued to reproduce the error -50 failure.

I then configured System Preferences->Energy Saver for both Battery and Power Adapter to "Put the hard disk(s) to sleep when possible". With that change I am no longer able to reproduce the failure.

So, I don't really like the idea of spinning down ALL of my drives (including the internal one) so with that objection aside the resolution above provides me with a suitable workaround.

[doublepost=1453299261][/doublepost]I had a similar problem.

My iMac has an external G-RAID connected via FireWire, where Time Machine stores backups from the internal hard drive. The "Put the hard disk(s) to sleep when possible" is not ticked, but this does not seem to affect the G-RAID. Time Machine will successfully back up, as long as the G-RAID is not "sleeping". Once it "sleeps", backup from Time Machine will fail with the -50 error message, and files on the G-RAID becomes read-only. Restarting the iMac makes the G-RAID writable again. No useful help from Apple support, only suggesting to reformat my 6 TB of data...

I attempted Wheelson's workaround and ticked on the "Put the hard disk(s) to sleep when possible" setting. This seems to have solved the case!

A big thanks to Wheelson!

 

[AzaraT]

For anyone stopping by - I had this problem too, none of the suggested solutions worked. The only thing that worked for me was a small app/script, Keep Drive Spinning that writes to a dummy files on the disk every so often to keep the harddisk from going to sleep. Not the best solution but only one that worked for me.