Looking for a good disk surface scan & repair

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Disk Keeper sorts out files and directory structures, but it can't repair bad sectors. or bad blocks. i.e., getting a few read errors on the Mini, and would like to do some sort of scan and repair. If possible.

in order to "repair" a bad sector, the data on the bad sector has to be moved out of the way, and then written back to disk. That process allows th OS to map out the bad spot so it doesn't get used again.
One way of doing this is for example, with a file called "unfortunate.log" that may be straddling a bad spot, then it needs to be deleted, the trash can emptied, then a new copy restored from the backup. As it's being written back to disk, the OS sees the bad sectors and maps them out of harms way.

Which is why
Booting from Recovery
Formatting working drive
Restoring from Time Machine will effectively map out any (new) bad sectors.

Except in the case of the bad sector being in the boot/recovery partition. Then you have a problem.

I think that's how it works
 
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cwa107


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There was a time when hard drives were extremely expensive and manufacturing was far less precise - and back in those days, we used tools like Disk Warrior and SpinRite to try to allocate out bad sectors and blocks in an effort to salvage the drive. In fact, it wasn't all that uncommon to have drives come out of the factory with bad blocks (which were allocated out in the drive's ROM).

Today, however, things have changed.... hard drives are dirt cheap. It will cost you less to replace the drive than it will to buy a repair tool. Additionally, a drive that suddenly starts having bad blocks is likely to continue to decline over time. So, repairing it by allocating out the bad spots is akin to trying to patch hole in a sinking ship. That ship is going to sink one way or another, it's best to get off while the getting's good...

So, my advice... worry less about buying tools to salvage what you have and begin shopping for a replacement. And while you're at it, might I suggest an SSD so the next drive is less likely to fail?
 
C

chas_m

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You can:

1. (following a complete clone backup, to an external drive) Boot from your clone and erase the hard drive, selecting to erase with zeros for a single pass. This will lock out bad sectors, and won't take days like the other options. Then clone back from your clone backup. This also does what people use to call "defragging."

2. Buy a replacement hard drive. Hard drives are stupid cheap these days, and a drive with problems is never going to get better, just worse.

(shakes fist at cwa for typing faster than me)
 
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yea, I know. But old habits die hard. Thanks guys.

I have Carbon Copy Clone, and SuperDuper!, both much the same.
Slowly getting the kit together to put a second HDD in my Mini, and as well have that all important Clone drive sitting there on a USB3. Plus the TimeMachine drive. The collection of drives is starting to build out of all sense.
and oddly enough, SSD's have bad blocks as well, although I don't know if they develop more, or just have some in the mfg process.
And there's another trap for unwary players. If you mix an SSD and a HDD in an Apple running I think 10.9 and up, or is it 10.8 up, it automatically tries to make you a fusion drive. I'm running 10.10.2 and it certainly will.
The other option I have of course is to stick my head in the sand and deny that there is ever any problems...
 
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forced fusion drive?

The comment below about a trap when mixing SSD and HDD in the same Mac seems incorrect today (Jan 2, 2017). I am running Yosemite (10.10.5) and I replaced my Macbook Pro's HDD with a SSD, then moved the HDD to the previous DVD drive position (using OWC adapters). The HDD just shows up as another drive. Maybe it's because the HDD was already formatted? So I now have very fast boot up (11 sec) with the cheap 120GB SSD, and access to lots of extra storage on the 750 GB HDD. Also that allows easy access from my desktop iMac to the HDD files as the HDD appears like a normal external drive. Oh, I kept the DVD drive using a box from OWC (they have a nice package to make SSD swapping very easy).

yea, I know. But old habits die hard. Thanks guys.

I have Carbon Copy Clone, and SuperDuper!, both much the same.
Slowly getting the kit together to put a second HDD in my Mini, and as well have that all important Clone drive sitting there on a USB3. Plus the TimeMachine drive. The collection of drives is starting to build out of all sense.
and oddly enough, SSD's have bad blocks as well, although I don't know if they develop more, or just have some in the mfg process.
And there's another trap for unwary players. If you mix an SSD and a HDD in an Apple running I think 10.9 and up, or is it 10.8 up, it automatically tries to make you a fusion drive. I'm running 10.10.2 and it certainly will.
The other option I have of course is to stick my head in the sand and deny that there is ever any problems...
 

Slydude

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I'm not sure I understand exactly what member ShanghaiTimes meant by that statement. I'm still looking for a specific reference whatever policy might have been behind that statement.

I can say that my 2008 MacBook Pro that has had an SSD as the main drive and a regular hard drive in place of the DVD drive for some time. It's currently running El Capitan and I have never been forced to make a fusion drive. I've had that drive configuration through the last several OS versions.
 

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