External backup disk fails regularly

It sounded like the remedy was close, but when I examined the /volumes directory, there was only one version of each disk -- the iMac internal hard drive, and the G-DRIVE external disk.

Following the other support article (TS2474) that you pointed to, I did a graceful shutdown to power off.

Then I powered on the iMac and went in to single user mode (press power button, then immediately hold the command key and the letter S key).

While I was there, and before any drives were mounted, I did a "fsck" on the internal hard drive. The fsck reported that some errors were corrected.

I then did the mount -uw /

and checked the /volumes directory. Again, there was only one version of each disk.

I rebooted and after the boot process completed, I initiated another time machine backup.

And it worked.

But it has done that before -- after a reboot, the time machine backups work for a while -- a few hourly cycles -- and then it once again complains that it cannot find the backup disk.

So now I am going to wait it out.

I opened the time machine preferences menu, and went to the "Select Disk" routine.

It shows what one could interpret as one backup disk, listed in two places:

1) the current backup disk

2) the same disk in the list of available disks

Or, perhaps, the problem has not been remedied.

When I click on the disk in the "current backup", it prompts me to REMOVE DISK.

When I click on the disk in the ist of Available Disks, it prompts me to USE DISK.

Of course, I cancelled instead of selecting, and I will wait it out to see if the problem is fixed or not.

If I have to shutdown again, I'll go into single user mode again and run another fsck on both the iMac internal disk and on the external disk, then reboot and take it from there.

It is an interesting problem, yes?

Jim Taylor

Winnipeg, Canada

It seems that I have to reboot each time the time machine cannot find the fire-wire-attached backup disk. After reboot, it finds the disk and does the time machine backups until -- and this may be a big clue -- until I leave my computer for a couple of hours, of for the night or for the day.

Then the energy-saving stuff kicks in, and the login window appears after a period of absence.

Sometimes I activate the login window as a security measure to lock my screen when I am not at my desk.

It seems that activating my login window suspends my login session until I return and enter the password to get back to my session.

I am only speculating here, and these ideas may be completely untrue and irrelevant to the problem.

Theory number one:

My speculation is that, if activating the login window to lock my screen has the effect of suspending my login session, that the time machine timer keeps ticking. But if my session is suspended, it cannot perform the hourly backup.

Eventually it is unable to find the external backup disk.

Theory number two:

My backup disk goes to sleep after a period of inactivity -- I haven't yet figured out if I can change this attribute or not. If the disk goes to sleep, perhaps the time machine is not able to wake it up, and so cannot find the disk.

I am able to wake up the backup disk by going to the Finder window and clicking on the disk and querying the contents. However, after the time machine is unable to find the disk, waking it up after the fact does not remedy the problem.

Theory number three:

The gods are displeased with me, and jerk me around with this backup disk problem.

Fortunately, this is an interesting problem. My bypass is to reboot when the time machine disk is not found, and to initiate the time machine backup manually.

Interesting or it, I am actively searching for a remedy.

Jim Taylor

Winnipeg, Canada

So far the external backup disk continues to fail regularly.

For the past couple of days I had to reboot in order to bring the external disk back online after it could not be found.

This afternoon when I rebooted, I got a message that "The disk you inserted was not readable by this computer." The action button choices were "Initialize", "Ignore", or "Eject".

I am beginning to think that the disk itself might be a lemon.

My wife has a similar external G-DRIVE disk attached as her time machine backup drive, and it has been working flawlessly since September 2012. I just checked it to be sure, and the latest backup was about half an hour ago on the regular hourly backup cycles.

I will likely take this disk back to the Apple Store where I purchased it, and exchange for another.

Does anyone have any comments or suggestions that might offer a solution on the present external disk?

To recap:

- I have reset the disk partitions from a boot partition to a non-bootable GUID partition

- I have erased and reformatted the disk at least three times

- I have run the disk utility "disk repair" on the disk several times. The first few times it repaire a couple of things, but the other disk repair runs were clean

- I have tried rebooting, and that seemed to work for a couple of hourly backup cycles, then today I got the "disk not readable my this computer" message.

- I have tried running fsck on my iMac internal hard drive; though fsck found a couple of things to fix, it did not affect the stability of the time machine external backup disk

- My MacOS Mountain Lion is fully up-to-date

- another problem I've been having is intermittent system hangs (frozen screen, keyboard frozen), but it is difficult to imagine that this problem is related to the time machine problem

I will click on the "Initialize" option and see what happens. At this point, there is not much to lose, as I do not have much confidence in the time machine backup data that is on this disk. I will re-comission my old Time Capsule backup disk for now, until I can fix or replace the external G-DRIVE disk.

Jim Taylor

Winnipeg, Canada

One last question:

Selecting the "Initialize" button simply opened the disk utiltiy.

My backup partition had been formatted as Mac OS Journaled (extended case sensitive)

I checked about the difference between "extended" and "extended case sensitive".

Some comments indicate that "extended" should be OK, and recommended that the partition NOT be "extended case sensitive". Apparantly some apps, even Apple-supplied apps, can run into problems with the case-sensitive formatting.

So erasing and re-initializing my partition, changing only the extended option to be not "case-sensitive", my time machine is backing up its 465GB of data once again.

After that first backup completes, we'll see what happens next.

I checked my wife's backup disk and hers is Mac OS Extended (Journaled), and is not case-sensitive.

Does anyone have any comments on case-sensive versus not case-sensitive with respect to the Time Machine backup disk?

jim Taylor
Winnipeg

The first backup (almost 470GB) to the re-initialized disk took a few hours, as expected.

This morning the backup had completed, and the disk was still available. I initiated another backup which completed OK, at about 08:25.

I created a few small test files with text edit, just to have something new on my internal disk for the time machine to back up.

Then I left the machine for a few hours to have breakfast and coffee with my wife, and wait a few hours to see what would happen with the backup disk.

About 15 minutes ago I came back to check it, and it appeared to be OK, but the last backup registered was 08:25, with no hourly backups indicated. I initiated a backup and it came back with the usual problem: "Time machine couldn't complete the backup... an error occurred while creating the backup folder".

Re-initializing the disk from "case sensitive" to not case-sensitive appears not to have been a solution to the probem. At least I can state that I have tested this attribute also.

I am coming to the conclusion that it is the backup disk itself, and not the Time Machine application nor the Mac OS X 10.8.2 nor the iMac hardware.

I am going to head back to the Apple Store and purchase a new backup disk. If it works properly, I will do a secure 3-times wipe of the old backup disk and return it to the Apple Store for a refund.

If anyone wants to talk me out of this, let me know of another solution to try.

However, I think I've run through all the list of remedies that should work, none of which have been "The Solution" to this problem.

The G-DRIVE web site support page does not appear to have firmware updates for their G-Drives.

Jim Taylor

Winnipeg

Last thing:

I swapped firewire 800 cables on the G-DRIVE box.

Years ago (1970's) there was an old server that worked when the doors were open, and failed when the doors were closed. After a week of technicians crawling all over the box to diagnose the problem, the office secretary pointed out that it worked when the doors were open and failed when the doors were closed. She asked if there was something about the doors. It turned out that there was a multi-wire flat cable on one of the doors, and it turned out to be a broken wire in the cable. When the door was open, the wire made contact and it worked. When the door was closed, the wire broke contact and it failed. At that time, the part cost about $3.00 to replace.

After reading through firewire discussions, there are many complaints about firewire in relation to external disks, so I thought that changing the f/w 800 cable couldn't hurt, and it might help.

After running the usual tests, I'll report back on the cable.

If that doesn't work, I'll make a trip to the Apple Store to get a replacement drive.

Oi.

JIm Taylor

Winnipeg

I bought the replacement external hard drive -- an identical G-DRIVE 4TB.

Did a graceful shutdown, removed the failing disk and plugged in the new disk.

Booted the iMac, it found the new disk as expected.

I opened time machine preferences, went to SELECT DISK, and selected the old disk that was still in the configuration for time machine. I REMOVED the old disk, closed time machine preferences, and did a graceful shutdown-reboot.

On reboot, the system prompted me whether I wanted to use the new disk as a time machine backukp.

YES, I said. It opened the time machine preferences, and this time the old disk was gone from the selection list. (Fortunately I gave distinct names to the external disks so it was easy to tell them apart)

After the reboot, the old disk was gone and the new disk was in the list and already selected.

I launched the backup -- a full backup of some 465GB.

I'll leave it alone to finish the backup, and leave it overnight to track the hourly backups.

The manager at the Apple Store was quite decent and agreed that I could return the old disk, and expressed hope that the new disk would fix the problem. I showed him the lengthy history of all the posts on this topic and he was satisfied that "due diligence" was complete. I purchased the original disk on January 19th, and today is the two-week limit on the store's returns policy. He agreed of the need to do a secure wipe of the old disk before returning it.

They did offer to make an appointment with the Genuis Bar to have a tech look at it and run diagnostics, but appeared satisfied that (1) diagnostics and remedies have been tried already, and (2) in principle I did not want to leave my populated backup disk with the store unless it had been wiped.

If the new disk works as hoped then I will do a secure wipe of the old disk before returning it to the Apple Store.

I'll keep you posted, hopefully tomorrow morning before heading off to work.

Jim Taylor

Winnipeg

The new disk, so far, appears to be backing up OK.

I wrote a little script to update a file every 45 minutes to ensure that there would be something new to be backed up every hour. Right now it is 7:30 am, and the last backup was taken at 7:10 am.

This looks encouraging. I'll check again tonight after work, and if the time machine backups appear to be OK, then I'll initiate the secure wipe of the old disk and get it ready to return to the Apple Store.

Jim Taylor

Winnipeg

The new disk is, so far, performing flawlessly, as it should.

Based on all the diagnostics mentioned in earlier posts, it is reasonable to conclude that the old disk was defective. Therefore I will initiate a secure data wipe of the old disk, and prepare it for return to the Apple Store.

Thanks to everyone who took interest in this curious problem and who provided valuable suggestions and advice.

Jim Taylor

Winnipeg, Canada

A final note -- I hope.

When I re-attached the old backup drive to do a secure data wipe, it appeared to interfere with the new backup disk, even though the old one was attached via a USB2.0 cable, and the new one on a 800 FireWire cable.

The "can't find the backup disk" error recurred, and I just let it be until the data wipe completed 30 hours later.

The old disk has been returned, and the new disk appears to be doing its job.

In checking some other things, I noticed that there were some old programs still in the automatic startup list (I found reference to them in the normally hidden system directory /Library/StartupItems

There were some old Norton anti-virus stuff, some old Virex stuff, an old LexMark printer driver startup -- all of these were left-overs that never got removed as I migrated my iMac hardware a couple of times and as I upgraded MacOS from Tiger to Mountain Lion.

I got rid of these after carefully checking that they were not required. Most were running the old PowerPC executable code and was not able to run on my newer Intel iMac (late 2010 vintage) under Lion and later.

There was also an old thing called "Retrospect", again not executable under Mountain Lion.

Sometimes I wonder how this old stuff that never gets fully removed hangs around, and if it can possibly interfere with the smooth operation of Mountain Lion.

I'll never know, I suppose.

As I have time I try to go through my Applications folder and test each app to look for obsolete stuff, and get rid of it.

Hopefully the story about the backup disk problem is over. I'll wait a few days and do one final update, unless the problem recurs. Oi.

Jim Taylor

Winniepg, Canada