Failed Disks in RAID 5

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Hi guys,


I've got an HP N34L which I've had running unRAID for some time now (about 2011'ish), have upgraded it over the years however haven't moved to version 6 as yet. I've been running WD Green disks in it without an issue and have only just had my first failure(s). After a power outage on Saturday afternoon, my parity drive and data disk 1 appear to have failed. Now I've managed to get unRAID to read and recognize Disk 1 again, however it's showing a red status next to it as opposed to green on the other drives, and red next to the parity drive which it doesn't recognize at all.


I've since installed a new drive for parity and run a full pre-clear on it, however even though I can select the new drive as the parity device, it's still telling me the configuration is incorrect. Surprise surprise. So, my question is, is there a way to force the Disk 1 online in order to rebuild the parity drive, and then I can replace disk 1 (which actually appears to be failing)? or am I completely stuffed, need to recover data from the drives individually and then re-create the array and copy the data back once completed?


Thank you in advance ;)





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What makes you think that Disk 1 is failing?    UnRAID marking it with a red 'x' just means a write to it failed - not that the drive is necessarily bad.  Posting a SMART report for that drive will give us a chance to say whether it looks OK.


Since you have had 2 disks get marked as failed you will not be able to do the normal 'rebuild' type recovery.    I would suggest the following as a way forward


  • make sure you know the serial numbers for the current drives (a screenshot is normally the easiest way to do this)
  • use the Tools->New Config option to reset the array.
  • assign the drives as required making sure you do not accidentally assign a data drive as parity (which would result in data loss).  In fact at this stage it can be a good idea not to assign parity at all - you can always do that later.  UnRAID will recognise data disks and leave their contents intact when the array is started.
  • start the array.    If all is good then you can assign parity and let it rebuild from the data drives.  Note that to rebuild parity successfully then all the data drives need to read without errors.  Make sure you do NOT select any option to format drives - that would result in data loss.

If the suspect 'disk1' shows as unmountable that will probably mean that there is file system corruption due to an earlier failed write and reiserfsck needs running against the disk to recover it.


If you definitely know you are going to replace disk 1 then you could start with the replacement disk in the array, and once the array is up mount the old disk 1 outside the array to copy its current contents to the array.  However if the SMART report mentioned earlier shows the disk is OK this is probably not necessary.

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Thanks for the reply, appreciated!


Disk 1 actually had a failed state for SMART detection after the power outage, however since removing/plugging back in it's come good however it's showing the red dot next to it. I'd assume that I can't start the array in the current configuration in any case because the Parity drive has since died? So the suggested course of action going forward in creating a new config would be the best course of action correct?


Kind regards,



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OK, so I've done as recommended and appears to have worked. Re-created the config minus the Parity drive, and was able to bring the array online. Checked data, all intact, have now assigned Parity drive as well currently syncing.


Cheers for the help, appreciated ;)



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