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Disk Re-identification count


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Can anyone explain to me when you run a monthly disk health report what the disk re-identification count is?  I've got one disk that has been slowly climbing and now is at 21.  I think last month it was 18, then 15, etc.  It has 0 bad sectors and 0 re-identification counts on it.  Should I replace it?

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Had a similar experience, only worse, as I kept getting "degraded", would run repair, healthy. Repeat. Checked w/ WDDiags, NO PROBLEMS but Synology continued to complain. (Ran SpinRite, no problems or sector issues there, either) The re-identify, degraded, repair thing continued for months, numbering in the 3-6 range, I forget. Finally replaced and it's been quiet ever since. Haven't re-purposed the 3T drive yet, but will see if it becomes un-healthy in a FreeNAS box or something.


Replacement, seems better than actually losing data. I WISH I could have gotten it covered under warranty as it was less than 3yr old w/ the standard WD-Red warranty, but couldn't get it to show any problems running WD-Diags.

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I replaced the disk and it's back to zero.  Funny thing is the SMART test on the Synology indicated no problems with the drive so does that mean Synology doesn't think this is a critical issue?  I've struggled to find anything about it on Synology's sites.  

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After the SMART test I ran a data scrubbing.  It's currently at 44% but I received this an hour ago.  Are these things on Disk 5 related to the NAS instead of the disk? (edit:  I just read the logs, bad sector found on new drive).  

Dear user,

The hard disk 5 on DS1 had an I/O error, but it is working properly now after several retries. It might have been caused by bad sectors. If this error occurs again, please back up your data and run the S.M.A.R.T. test on your hard drive to examine the hard drive status.

Synology DiskStation

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I just installed a third drive into bay 5.  Their response was insightful:

Disk Reconnection Count, Bad Sector Count and Disk Re-identification Count indicate the total quantity of events that have occurred on your disk or system. Your data are still safely stored on the disk. Although these parameters provide early warning and information about disk health trends, they do not directly imply imminent disk failure.

The system has tried to reconnect to the disk for 2 times. Disk Reconnection Count display the sum of S.M.A.R.T. Attribute “UItraDMA CRC Error Count” and other interface issues detected by the system. If this parameter increases abruptly compared to general tendency, it may indicate that the disk or some hardware components are aging.

If you want to know more about SMART, this is a good resource:


We would also recommend running the Extended SMART test over the quick one since the quick can miss a lot of the signs that a drive is failing and the extended is more thorough.

This is a hard drive issue since it is more likely for the hard drive to fail than it is for the drive bay to go faulty due to the nature of mechanical parts. This is definitely not a software issue or bug.

Please start looking into replacing these hard drives reporting bad sectors.

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  • 3 weeks later...

So the first disk with the reconnection count issue passed a smart test on a separate machine using the HD MFG's software to test.  Now I'm not sure what to do with it.  I don't want to put it back in the NAS.  

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