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External hard drive disc sector failure...what can I do?


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#1 JimmyJam019

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Posted 24 January 2015 - 10:51 AM

Hi guys,

 

I was recently transferring a large file to my external cineraid hard drive.  It is a unit that contains 4 hard drives in it.  I have it setup on a raid 5.  However, during the transfer, my computer froze.  When I rebooted the computer and hard drive the folder was gone.  I ran a disccheck and it only recovered partial of the files with the rest being disc fragments.  I'm trying to understand what happened here.  Wouldn't the raid be able to save me in this situation?  It didnt do anything.  Also, is there a chance I could recover all the files?



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#2 zcomputerwiz

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Posted 24 January 2015 - 10:05 PM

If you turn off a raid array during a write operation you will lose data, and not necessarily just the new data you were writing since it can corrupt the filesystem.

Do you have another copy of these files?


Have you tried turning it off and on again?


#3 JimmyJam019

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Posted 25 January 2015 - 12:08 AM

If you turn off a raid array during a write operation you will lose data, and not necessarily just the new data you were writing since it can corrupt the filesystem.
Do you have another copy of these files?


I never turned off the raid array. Are you saying when I write data the raid will not protect me? I don't have another copy of the files

#4 Rrocha

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Posted 25 January 2015 - 08:55 AM

probably, the scheduler has not had selected different disks or didn't generated the blocks containing the addresses of other discs.

 

Take a look this explanetion of the datas.

RAID level 5

RAID 5 is the most common secure RAID level. It requires at least 3 drives but can work with up to 16. Data blocks are striped across the drives and on one drive a parity check sum of all the block data is written. The parity data are not written to a fixed drive, they are spread across all drives, as the drawing below shows. Using the parity data, the computer can recalculate the data of one of the other data blocks, should those data no longer be available. That means a RAID 5 array can withstand a single drive failure without losing data or access to data. Although RAID 5 can be achieved in software, a hardware controller is recommended. Often extra cache memory is used on these controllers to improve the write performance.

RAID-5.gif

Advantages

Read data transactions are very fast while write data transactions are somewhat slower (due to the parity that has to be calculated). If a drive fails, you still have access to all data, even while the failed drive is being replaced and the storage controller rebuilds the data on the new drive.

Disadvantages
  • Drive failures have an effect on throughput, although this is still acceptable.
  • This is complex technology.
Ideal use RAID 5 is a good all-round system that combines efficient storage with excellent security and decent performance. It is ideal for file and application servers that have a limited number of data drives.

 

http://www.prepressure.com/library/technology/raid



#5 Kilroy

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Posted 25 January 2015 - 10:09 AM

RAID protects you against hard drive failures, that is all.  RAID does not protect against virus infections or corrupted data, a back up should still be necessary.

 

How is the RAID attached to the machine?  If it is attached via USB you may have interrupted the write corrupting the data if it was set to cache data.



#6 JimmyJam019

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Posted 25 January 2015 - 02:06 PM

RAID protects you against hard drive failures, that is all.  RAID does not protect against virus infections or corrupted data, a back up should still be necessary.
 
How is the RAID attached to the machine?  If it is attached via USB you may have interrupted the write corrupting the data if it was set to cache data.


They are attached via USB 3.0

#7 JimmyJam019

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Posted 25 January 2015 - 02:12 PM

Whenever I try to access the other files on the drive now a message pops up that says. "Device I/o device error"

Edited by JimmyJam019, 25 January 2015 - 02:13 PM.


#8 JimmyJam019

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Posted 25 January 2015 - 02:14 PM

I'm not even sure what I can do with these drives now. Should I reformat? But even if I do is my data safe or is one of the drives failing?

#9 Kilroy

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Posted 25 January 2015 - 10:35 PM

You can try Hard Disk Sentinel's trial to see if there is something that tests bad.

 

You can try SpinRite (not free).  If you go with SpinRite you'll pull the drive from the external case and install it in a PC and run it.

 

I'm not sure you're going to be able to get the error corrected, no matter what you use.

 

This is why I stopped using RAID on my machine.  I had a 6TB RAID5 array set up, and it dumped 4TB of data.  I decided my data was safer on single drives.  I use Hard Disk Sentinel Pro to monitor my 18 disks, eight of which are in external enclosures.






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