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Scanner and bad sectors...


thepregnantgod

Question

In my transition from Drivebender to Drivepool/Scanner combo I'm noticing that a number of my 20 3-4 TB drives have bad sectors.  In fact, my brand new WD Red 4TB drive had an unreadable sector out of box!

 

That being said, a few questions:

 

1. At what point should I look to RMA (if under warranty) a drive?  How many unreadable sectors?  I know that once one is identified the drive uses a different/replacement sector and some such...

2. After Stablebit scanner identifies the bad sector does it (on a firmware level) have the drive mark it as bad and thus it will be skipped if data is written to the drive?  Or...is this dependent on Stablebit scanner being installed?

3. How often is too often to scan the drives?  The default is 30 days but finding these bad sectors is frustrating and I'd rather identify them before I write data across them.

4. If I reinstall the OS - will all the drives need rescanning? Or will Stablebit somehow know that the drive has been recently scanned and marked healthy?  (I'm assuming no)

 

Thanks.

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That depends, really.

 

  1. If you have a lot of "uncorrectable sectors", or if this value, or reallocated sectors count RAPIDLY increase, then you should RMA the drive (or more than 100 for either).
  2. Independent. We will identify bad sectors, but we do not write to them. Ever. The reason being that if you write to them, then you can no longer recover the data. 
    Additionally, they will "go away" normally, the next time they are written to (the firmware automatically reallocates the sector, and your "reallocated sector count" should increase when this happens, I believe).
    If you wish to force the bad sector to be fixed, run "ckdsk x: /r", where X: is the drive in question. This attempts to recover bad sectors, or force the disk to reallocate them. Additionally, if you're using Windows 8 or 8.1, or Server 2012, or 2012 R2, you can add "/scan" to that command to run it "online" (so the disk can be used while scanning, isntead of knocking it completely offline)
  3. Actually, writing data is how they're "fixed". But I understand what you mean.
    As for how often? If you're adding a LOT of data regularly, then maybe every 7 days (once a week) may be a better option. However, since you're reading when scanning, there shouldn't really be a "too often" here. Additionally, the scan may trigger the disks internal error correct and remap sectors before they become a problem (which is what is supposed to happen normally)
  4. If you reinstall, then the disks will need to be rescanned, as that logging data will be wiped. You can mark the disks as "good" to delay this, though.

I think I've covered everything sufficiently here. If not, then please ask away!

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Independent. We will identify bad sectors, but we do not write to them. Ever. The reason being that if you write to them, then you can no longer recover the data. 

Additionally, they will "go away" normally, the next time they are written to (the firmware automatically reallocates the sector, and your "reallocated sector count" should increase when this happens, I believe).

If you wish to force the bad sector to be fixed, run "ckdsk x: /r", where X: is the drive in question. This attempts to recover bad sectors, or force the disk to reallocate them. Additionally, if you're using Windows 8 or 8.1, or Server 2012, or 2012 R2, you can add "/scan" to that command to run it "online" (so the disk can be used while scanning, isntead of knocking it completely offline)

 

Is there any chance we could see a manual option to rewrite the bad sectors? I understand why you don't have an automated process to deal with them, but it seems like a manual option would make more sense than running chkdsk /r.

 

A couple things I would like to see:

 

1) If the file is duplicated, then an option to rewrite that file with the known good version.

2) If the sector is unallocated, then an option to zero it out.

3) If the file is not duplicated, then a notice that action can't be taken until the file is removed.

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We are definitely looking into implementing something like this. 

And yes, it would definitely be a manually initiated process (after writing, data recovery become significantly harder).

 

  1. That would require a significant change to both DrivePool and Scanner.
    I'm not saying it won't happen, but it would be a lot of work. 
    And it is a very good idea.
  2. Yup, definitely. Or 1's. or randomly decide. Depends on which is the best method, or if we add options on how to handle that.
  3. Well, we have the file recovery option. At worse, have users be prompted to run it BEFORE attempting to overwrite it.
    Or attempt to read it and if we can, then overwrite it with the original contents.

So we've definitely thought about it. :)

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Hi I feel I his pain on point 1 I have had this a couple of times where a file is bad but there is a duplicate hidden somewhere I have also asked to see if anything can be done on this it is really really frustrating to know there is a duplicate of a file but you have no access to it that's like having your hands tied behind your back.

 

The only way I know and found that helps with the damaged file recovery is to remove the drive the file is on let drivepool reduplicate from the duplicates then format the removed drive and add it back to the pool this can up to 6hrs to complete and is messy to say the least.

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Hi I feel I his pain on point 1 I have had this a couple of times where a file is bad but there is a duplicate hidden somewhere I have also asked to see if anything can be done on this it is really really frustrating to know there is a duplicate of a file but you have no access to it that's like having your hands tied behind your back.

 

The only way I know and found that helps with the damaged file recovery is to remove the drive the file is on let drivepool reduplicate from the duplicates then format the removed drive and add it back to the pool this can up to 6hrs to complete and is messy to say the least.

Definitely, and this is something we could streamline and integrate better. I'll bring this up to Alex.  

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