thedispatch

Q: Time Machine corrupting external USB hard drives

In February I installed two Mac Minis running 10.8 Server. Each machine had an external hard drive connected to it.

 

Sometime over the Labor Day weekend, both drives stopped working. When I came in Tuesday, each machine had a message on the screen that the Time Machine drive had been improperly ejected. I powered down both drives and then powered them back up. Here's what is going on with each machine:

 

MACHINE #1:

Has a Western Digital 1TB drive formatted as OS X Extended Journaled.

 

Disk Utility is able to see the external drive; however, whenever I try to back up, I get the message "Time Machine couldn't complete the backup... Files can't be copied onto the backup disk because it appears to be read-only."

 

In Disk Utility, if I select the partition and Verify Disk, I get the message "Disk Utility stopped verifying Backup. Couldn't unmount disk."

 

When I try to reformat the drive, I get the message "Disk Erase failed. Disk Erase failed with the error: Couldn't unmount disk."

 

The Time Machine System Preference pane shows "None" for both oldest and latest backup times; however, I am able to enter Time Machine and see files going back to April.

 

MACHINE #2

Has a Segate 2TB drive formatted as OX X Extended Journaled.

 

Initially Disk Utility would recognize this drive about 50% of the time. I would power it down and back up. Sometimes it would appear in Disk Utility, sometimes it wouldn't. Whenever I would try to verify or repair this disk, it would immediately unmount and I would get the message that the disk was not ejected properly. When I try to backup using Time Machine, TM acts like it is preparing to back up and then the disk disappears from Disk Utility and from the Desktop and I get the message that The disk was not ejected properly.

 

This machine showed it was last backed up on September 1.

 

After fiddling with it, I was able to format the drive. After formatting the drive, I started a Time Machine backup and the drive unmounted again.

 

 

It seems that some event over the weekend caused both drives to corrupt. There was no sign of a power-outtage. Can anyone suggest how I can track down what caused this? Would there have been a maintenance script that would have run on Sept 1 that could have messed both drives up? Some other system event? Losing the data isn't a big deal. I just want to make sure I prevent whatever caused this in the future. Any tips would be much appreciated.

Time Machine, OS X Mountain Lion (10.8.4)

Posted on Sep 3, 2013 2:37 PM

Close

Q: Time Machine corrupting external USB hard drives

  • All replies
  • Helpful answers

  • by Linc Davis,

    Linc Davis Linc Davis Sep 3, 2013 4:06 PM in response to thedispatch
    Level 10 (207,926 points)
    Applications
    Sep 3, 2013 4:06 PM in response to thedispatch

    You're describing the symptoms of a failed drive or a failed logic board. Those rare events couldn't have occurred at random on two different machines at the same time. If they're both connected to the same power source, a voltage surge could have done it. I suggest you try a new drive.

  • by Erick666,

    Erick666 Erick666 Sep 3, 2013 6:51 PM in response to thedispatch
    Level 1 (0 points)
    Sep 3, 2013 6:51 PM in response to thedispatch

    I had the same problem. September 1st was the latest backup, also. No power issues. Computer has been up, except for restarting it to attempt to get Time Machine running again. Still no luck.

  • by thedispatch,

    thedispatch thedispatch Sep 4, 2013 6:27 AM in response to Linc Davis
    Level 1 (0 points)
    Sep 4, 2013 6:27 AM in response to Linc Davis

    Both computers and external drives are on a good surge protector strip which is in turn hooked to a batter back-up device.

  • by Linc Davis,

    Linc Davis Linc Davis Sep 4, 2013 7:05 AM in response to thedispatch
    Level 10 (207,926 points)
    Applications
    Sep 4, 2013 7:05 AM in response to thedispatch

    I don't know of any way you can determine what caused the malfunctions. You can look at the logs, but I wouldn't expect them to tell you anything useful.

  • by thedispatch,

    thedispatch thedispatch Sep 4, 2013 7:20 AM in response to Linc Davis
    Level 1 (0 points)
    Sep 4, 2013 7:20 AM in response to Linc Davis

    Yeah, I don't know much about the logs. I flipped through some using Console but didn't really know what I was looking for. I was hopeing to see an event that was followed by a notice that the USB drives had been improperly ejected since that was a message I received on both machines.

     

    Since both machines were affected at the same time it seems logical it would be a scheduled event or, as you suggested, some power issue.

  • by Bronweg,

    Bronweg Bronweg Jun 17, 2016 3:54 PM in response to Linc Davis
    Level 1 (5 points)
    Jun 17, 2016 3:54 PM in response to Linc Davis

    A hardware problem can certainly cause this. But before throwing out the drive make sure there is a problem with the drive. I have had the same thing happen (except never on two drives at once) at least a dozen times and have never found a problem with the drives. This has happened on two different MacBook Pros and two different Mac Minis running several versions of OS X. It has happened with a number of external disk drives from Seagate and Western Digital. All of these drives have tested OK and have been successfully reused in other applications on Macs and on Windows systems. (In case there really might be a hardware problem I avoid using the drives for Time Machine after erasing them to clear the error.)

     

    Additional notes: The Mac Minis are on UPS and did not have power drop. The last time this happened was this morning, on a MacBook Pro connected to a power source, an hour following a successful Time Machine backup. I have not found a solution, so I am using a cloud backup service in addition to Time Machine.

  • by BDAqua,

    BDAqua BDAqua Jun 17, 2016 4:31 PM in response to Bronweg
    Level 10 (123,501 points)
    Jun 17, 2016 4:31 PM in response to Bronweg

    Are these Bus powered drives or do they have AC power supplies?

     

    Are you running any software that came with these drives?

  • by Bronweg,

    Bronweg Bronweg Jun 17, 2016 8:45 PM in response to BDAqua
    Level 1 (5 points)
    Jun 17, 2016 8:45 PM in response to BDAqua

    Thanks for your reply. This problem was first seen on a drive with an AC adapter, but I have seen this problem on bus-powered drives as well as drives with an AC adapter. Today's occurrence was with a bus-powered drive. I had mixed success with using the software that comes with the drives and only used it on one of the older systems before deciding that it was not doing anything useful for me. It is not in use on the system on which I saw today's problem.

  • by BDAqua,

    BDAqua BDAqua Jun 17, 2016 11:11 PM in response to Bronweg
    Level 10 (123,501 points)
    Jun 17, 2016 11:11 PM in response to Bronweg

    Not sore what is going on, but I find Bus powered drives a constant problem, then awhile back there were AC powered drives with flaky power supplies, I'd thy an AC powered USB hub for the Bus powered drives.

     

    Other than that it might be the USB cable(s)