OS X Lion – read/write permission problem GTech external drives

[Hugh Hartford]

I have this same problem with a 4TB Gtech raid drive on macs using OS X 10.6.8. The drive mounted with an error message and although all the files are there the drive can no longer read/write and Disk Utility can’t verify disk. I am copying all the data on to a working drive now but wanted to work out what caused it so can avoid this happening again.

I’m not sure it is the operating system as it has the same problem on another mac running OS X 10.7.5

Any thoughts would be appreciated.

[Sean Eunson]

This sounds like a different problem. I was always able to “read” the files but not always able to write to the drive.
Verify drive fixed the problem and I have only occasionally had the “write” problem come back. I have had no problem otherwise with my drives and have been editing with them for awhile.
Sometimes you do get a bad drive – although the GTechs have been rock solid for the most part.

[Hugh Hartford]

Thanks for the response, you’re right I can ‘read’ the files – many quicktime clips still play, but nothing can be copied to the drive and no files on the drive can be changed. When transferring the data off the drive there were about 5 video files (out of 2.5TB of data) that made the transfer crash and I’d have to relaunch finder. Could it be that these files corrupted and caused the problem with the drive? Just trying to avoid it happening again.

[Sean Eunson]

It does sound like a corruption problem. One thing to be careful about with any drive is a hard ejection off of the computer. You know – when you get that red letter warning when you have accidentally turned a drive off. I almost always run “Disc Warrior” on that drive afterwards.

[Mary ann Land]

My iMac keeps getting hung up, especially when I use Microsoft Word. Then I have to do a cold re-boot. Is this what is causing problems with the permissions. I recently sent my external drive unit back to the manufacturer to get some help. They said they couldn’t access any files or see any files at all. I got it back from them and I could see all my files just fine. But now I can’t save a file that I pulled up off the external drive to work on. I was able to see the drive and now it isn’t even showing up at all. It’s not mounting. I did a Verify Disk and a Repair Disk. It keeps saying Invalid key length. The volume OWC Mervury Elite Pro Qx2 2 First 4 TB could not be verified completely. Error: This disk needs to be repaired. Click Repair Disk.
I did it again and it says Error: Disck Utility can’t repair this disk…Back up as many of your files as possible, reformat the disk, and restore your backup-up files. Before I tried to repair the disk, all my files were there and the unit was mounted just fine! Now I can’t even access it. What can I do now? Thank you.

[Sean Eunson]

This sounds like a drive that totally needs to be wiped and reformatted. If the manufacture could not find a problem with the drive (and ill assume they did a read/write test and diagnostic) then I would dump your files off of the drive and totally re-format it as a Mac drive . But if this does not work – if possible return the drive.
My problem in this thread was different and I had no “read” problems just a “write” permission problem.

[Michael Wright]

I have the same problem on my QNAP NAS. I am a long term Windows user – having been using Mac for past 3 years. This read/write problem and permissions is a constant pain. No-one seems to have the answer.

I can access the NAS on my Windows machines with no problems at all. All permissions are set correctly on the NAS. I am the sole user of the MAC and am, therefore, the admin. I should have full permissions for all MY drive and the files they contain. This is just not the case.

For an OS X touted to be the most advanced in the world – it is a mess. Permissions is a fundamental thing that should just work. The user should not be having to repeatedly mess around with disk utility of the terminal.

Not much more hair left to pull out.