# How to check for bad blocks?



## kon21 (Sep 6, 2004)

I have a hard drive which is failing 10.3 installation even after a format/repartition.
I want to verify that the hard drive has no bad blocks. Which utility can I use to verify the HD integrity?

TIA


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## Pengu (Sep 6, 2004)

Use disk utility on the OSX install disc


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## perfessor101 (Sep 8, 2004)

Disk Utility does not do a surface scan which is what you need to find bad data blocks on the drive. The only two apps I know of that do that with OS X are Drive 10 1.1.5 and TechTool Pro 4.0.3. Both are from Micromat. In most cases the only cure for a bad data block is to erase the drive with the write zeroes option which works as long as there are enough spare data blocks available to remap the bad blocks to. 

If you have data blocks failing at a high rate the S.M.A.R.T. values should tell you that the drive is failing. You can check this in Disk Utility by selecting the drive, not the volume on the drive, and checking the S.M.A.R.T. status in the lower right side of the window. If the status is anything but "Verfied" run, don't walk, to your nearest computer store for a new drive. TechTool Pro will give you each of the individual S.M.A.R.T. readings.


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## ElDiabloConCaca (Sep 8, 2004)

Actually, using the "write 0s" option will essentially do the same thing that a surface scan will do -- since the formatter will try and write 0s to all the blocks on the disk, if it encounters any blocks that cannot be written with a 0 (bad blocks) it will make a note of that in the partition table and mark that block as unusable.

The only catch is that this is a "destructive" bad block test, since you must format the drive to use it.  It is true that if you want to simply test for bad blocks without wiping the drive clean, you must purchase 3rd party surface scan software.


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## perfessor101 (Sep 8, 2004)

ElDiabloConCaca said:
			
		

> ... it will make a note of that in the partition table and mark that block as unusable


And remap the location to one of the "spare" data blocks that are included on every drive. If all the spare data blocks have been used, that is a strong indication the drive will be failing completely and much sooner than later. This shows up in the S.M.A.R.T. values reported by the drive firmware.

The destructive nature of the erase with write zeros option is a *HUGE* catch. Which is why I always try Drive 10 or TechTool Pro surface scan first.


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## macosx2012 (Sep 13, 2012)

PBD(Partition Bad Disk) can be used to verify the HDD integrity. It can not only detect the bad sectors, but also isolate them and create healthy partitions.



kon21 said:


> I have a hard drive which is failing 10.3 installation even after a format/repartition.
> I want to verify that the hard drive has no bad blocks. Which utility can I use to verify the HD integrity?
> 
> TIA


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## DeltaMac (Sep 13, 2012)

Thanks, "macosx2012" for telling us about a Windows app.
It won't run under OS X (not without using one of the Windows solutions, anyway)


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## Giaguara (Sep 13, 2012)

... Which also won't work on a Mac running Mac OS X 10.3, which the original poster was using in 2004 when this thread was created.


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