3 bad sectors have appeared on my External HD - any advice?

[Siriosys]

Hi,

I have a 2 year old external HD (Samsung HD753LJ), which has 3 partitions. One for my TM backups, the other with just straight data and a FAT partition for WIn compatibility.

This evening while reading some files off the non-TM partition, I noticed the drive 'ticking' and then got a read error.

I ran up Drive Genius-2 and it found 3 bad sectors. I'm not too worried about the file as I can replace it, however I was unable to find a way to repair the sectors without destroying the entire drive's contents.

My questions are as follows:

How can I do a non-destrucive sector repair without losing the entire drive?
If yes, can anybody tell me what software I should use?
Should I be replacing the drive even if only 3 sectors have gone bad?


Would really appreciate your help although it's not 'critical' yet.



Regards



Rob

 

[BlueRevolution]

If it's making noises, the drive is likely about to die. Back all of your data up now.

 

[Siriosys]

Hi BlueRevolution,

It's only making the ticking noise when trying to access the file that is located on the 3 bad sectors. Other than that, the drive seems to be fine.




Regards

 

[nebarik]

these issues arnt fixable. your drive is about to die, buy a new one, back up what data you can. simple as that

 

[Makosuke]

The ticking noise is it repeatedly trying to read the bad sector, and is the expected behavior. I believe some drives will automatically re-map a bad sector in firmware when they attempt to write to it, so you might only notice this when trying to read a file written before the sector failed. Deleting the file located there (with "Secure Empty Trash") might be sufficient to get the drive to remap that sector, though it might also take a full reformat.

I don't know because, like BlueRevolution said, if the drive is developing new bad sectors it's more than likely on its way to the grave, so my response at the discovery of bad sectors is usually to backup whatever's on it, and either get it RMA'd or toss it if it's out of warranty.

A single bad sector could, I suppose, be "natural", or the cause of getting physically bumped while writing (in which case I'd DEFINITELY stop using it), but I'd be very skeptical. In my experience any drive that had developed bad sectors would usually reveal more after every low-level format, indicating progressive failure. I pretty much keep running whatever tester the drive manufacturer wants before they'll replace the drive until it eventually shows a failure code... which it inevitably will sooner or later.

Bottom line: If it's out of warranty (sounds likely for an external), back up what's on it and buy a new one. If you're really desperate you could reformat and then rescan and hope to get lucky, but I wouldn't risk my data that way. Don't know how easy those cases are to crack open, but if you can get in and aren't averse to mucking around with the guts you might be able to salvage the case and just put a fresh internal drive into it.

 

[Siriosys]

Thanks for your replies!

I'm not at all worried about cracking open the lid and replacing the drive. I was just hoping for a less task-intensive route.

It's a MacPower external box attached to the FW800 port with a Samsung drive inside so I can easily rip it open and replace the drive which I'll get onto early this week.

Given that this drive is my Time Machine disk as well as having 2 other partitions and larger than my Internal Mac drive, does anybody know if cloning the drive will be sufficient to get TM working back the way it was as well as the other partitions?

Would something like Carbon Copy Cloner or iPartition do the trick?



Regards


Rob

 

[Siriosys]

Well, I've done a stack of reading over at the CCC forums and also some other sites relating to cloning a HD, however I'm a bit stuck on a few points.

Professionally, I work with both Norton Ghost and Acronis True Image which, in the Windows Environment, seems to be able to to perfectly make an image of an HD, regardless of how many partitions there are and in the case of TI, can even work with disks as part of a RAID set, however it seems that such a simple 'click-next-next-Finish' approach doesn't exist with OSX.

I have come across some material that suggests that it's not possible to completely image a drive that has a Time Machine partition on it.

Does anybody know if this is true?


Regards

 

[BlueRevolution]

I've never tried cloning a Time Machine partition, but I do know that Carbon Copy Cloner can only clone one partition at a time, not an entire drive.

 

[Makosuke]

Well, if the replacement drive is exactly the same size as the original, I'm pretty sure that CCC is capable of block-level copies now, which would result in exactly the same partition structure on the new drive as the old. That's the same thing Ghost uses in this circumstance, so I expect the result would also be the same.

Here's a MacOSXHints tip with some other suggestions, and a blog post explaining the same process in more detail, and with illustrations.

And you've sure had better luck with Ghost than I; I use it at work as well, and while it will, indeed, produce a bootable Windows clone, Symantec's support/update system manages to give Adobe's a run for its money in terms of customer-hostile stupidity.

Most maddening was an earlier version that wouldn't work with SATA drives properly, resulting in a misleading error well into the clone operation. There WAS an update to fix this problem, but for some reason Symantec decided not to put it on the normal update server, meaning that while the updater TOLD you the software was up to date, if you somehow managed to find the technote explaining this, you could type in the magical "old" update server manually at which point it would find and install the update allowing it to work properly. The day I found that out (after way too many hours of trying voodoo suggestions from other technotes for the same error) was the day I stopped buying anything from Symantec.

 

[BlueRevolution]

Yes, Carbon Copy Cloner has been able to perform block-level clones for a few years now, but it can still only clone one partition at a time. The two drives need not be the same size, either. A block-level clone can take place from a smaller drive to a larger one.

As you can see in the shot below, only partitions are listed, not drives.

 

[Siriosys]

And you've sure had better luck with Ghost than I; I use it at work as well, and while it will, indeed, produce a bootable Windows clone, Symantec's support/update system manages to give Adobe's a run for its money in terms of customer-hostile stupidity.

Most maddening was an earlier version that wouldn't work with SATA drives properly, resulting in a misleading error well into the clone operation. There WAS an update to fix this problem, but for some reason Symantec decided not to put it on the normal update server, meaning that while the updater TOLD you the software was up to date, if you somehow managed to find the technote explaining this, you could type in the magical "old" update server manually at which point it would find and install the update allowing it to work properly. The day I found that out (after way too many hours of trying voodoo suggestions from other technotes for the same error) was the day I stopped buying anything from Symantec.

LOL!...........Oh boy, you've just given me a case of Post Traumatic Stress Disorder!!!...........had almost the same thing - I now use Acronis True Image for most my work and have had huge success with it. Manages to work its magic in RAID environments as well - seems to even sort out IBM's ServeRAID setups which is no easy task!.

 

[Siriosys]

Thanks guys, the feedback has proven valuable and I've also discovered that I have a tool sitting in front of me that I didn't even realise would do the job - Drive Genius2 - Praise be to the MacUpdate promos!!!!

Turns out that it natively does 'device to device' cloning regardless of Partition types so as soon as a new HD arrives on Monday afternoon, I'll set about cloning my drive.

I'm actually interested in the CCC one as well so I'm gonna test it to compare the two product's results.

Feel a bit stupid for not realising that Drive Genius2 was up to the task, but have just finished reading a comparison of various Disk management utils online and they made mention of it.


Cheers!


Rob

 

[Makosuke]

Some good educational info in this thread. Not having tried CCC's block-level copy it's good to know that it's only at the partition level, and even better to know that Drive Genius 2 can do that--I'd used some of its other features, but hadn't even looked at the cloning features.

Also glad to hear that I'm not the only one who got traumatized by Ghost. I'll definitely check out Acronis True Image the next time I have need for a Windows cloning utility.

 

[gr8tfly]

Some good educational info in this thread. Not having tried CCC's block-level copy it's good to know that it's only at the partition level, and even better to know that Drive Genius 2 can do that--I'd used some of its other features, but hadn't even looked at the cloning features.

Also glad to hear that I'm not the only one who got traumatized by Ghost. I'll definitely check out Acronis True Image the next time I have need for a Windows cloning utility.

Disk Utility will do a block copy if you check "erase destination" (under the "Restore" tab). Since it needs to unmount both the source and destination volumes, you need to run it off your install DVD (or boot off another drive). This will create a bootable clone of your source volume. (I use Disk Utility exclusively when making image backups or moving/upgrading drives.)

 

[Siriosys]

**All Sorted**......read on if you want the details....

Firstly, many thanks to you all for posting and helping even though I have found a solution not listed above, it set me on a bit of a path of discovery which is always good for learning.

I'm back up and running with a new 1Tb Western Digital Greenpower HD.

The process I decided to adopt was as follows:

after unmounting my existing Samsung Drive, turning off Time Machine in its preferences pane and attaching a new WD drive to a cradle connected to USB Port I started up Drive Genius 2 which I had got from a previous MUPromo Bundle - costs $99 normally.

I ran the scan on my old drive again and as expected, it found the faulty sectors. it's worth noting that Drive Genius DOES NOT REPAIR BAD SECTORS with it's scanning tool. The manual even eludes to this suggesting backing up your data and doing a drive replacement.

Next, I used the Duplicate function from its menus. You can either duplicate individual partitions or an entire Drive. The latter of these was suited to my requirement to get an exact replica of my failing Samsung drive which was configured with 3 partitions (TimeMachine / FAT / MacOS Extended).

7 hours later (yes, it's VERY slow!) - I was greeted with an error message suggesting there had been an internal error which I suspect was the faulty sectors, however it said the duplication job had completed successfully.

While the drive was unmounted, I performed an ADU - Verify just to make sure everything was going to be ok on the outset, and lo and behold - it was!

My last and final test was to restart my mac and re-enable Time Machine. Once enabled, i then used it to restore some files from the first backup set (June last year) and this completed without a hitch. Lastly, I kicked off a manual backup to capture the last 4 days worth of changes and this worked fine.

All up, a good learning experience and a lucky save from potential data loss, however, I can't help but consider that either RAID1 or 1e would be a preferred option for dealing with a backup disk subsystem hardware failure.

Now the only task left to do is to expand my Time Machine backup partition as it's getting pretty low. I noticed that the first thing TM tried to do was delete old backups when it started it's first automatic backup after I'd finished.......woooops.