Confusion over raid errors.


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First off, sorry if this comes up often however seeing so many threads and information it's coming across to me as very varied in the solution.

 

I have quite a simple unraid setup.

2TB - WD Green (Parity) 

2TB - WD Green (Disk 1)

2TB - WD Red (Disk 2)

2TB - WD Red (Disk 3)

 

I originally started out with just the two greens then later added the Red disks as I managed to get them off a friend brand new for free. These are roughly 2 weeks old.

 

As of today I noticed a few notifications about `reallocated sector ct is 160` (Disk 1) I noticed this number is climbing, so I immedaitely started copying data from this drive to another drive (Disk 2). Now I am about 20% through the copy and have noticed that Disk 2 is showing as errors, however smart scans on both drives are passing so I am slightly confused as to what is happening here. My immediate plan is to take data off Disk 1, copy it to Disk 2 and take Disk 1 out of the array. But now seeing errors on disk 2 has got me thinking that this may not be the best plan?

 

I'd love some input here.

 

 

chipshop-diagnostics-20190320-2121.zip

124.JPG

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Disk2 looks OK, maybe just a bad connection.

 

Disk1 not OK but also not disabled. The normal recommendation would be to replace it, but you mentioned removing it instead. Do you mean you want to have one less disk for now? Or do you intend to put another disk in its place?

 

Do you have another copy of anything important and irreplaceable?

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I don't have any backups at present it's just media that I have downloaded. I don't have a spare 2TB disk to replace it with, but I was planning on adding a 1TB disk in it's place. I don't really understand how this raid works if I am required to backup the data, perhaps I am a bit ignorant here.

 

Should I power down and reseat Drive 2? I use a Gen 7 microserver.

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9 minutes ago, runtman said:

I don't really understand how this raid works if I am required to backup the data

Parity is no substitute for backups, regardless of RAID or Unraid. Plenty of ways to lose data that don't involve a bad disk, including simple user error. You must have another copy of anything important and irreplaceable. You get to decide what qualifies. If none of this data qualifies, that's fine.

 

13 minutes ago, runtman said:

I was planning on adding a 1TB disk in it's place

You can't replace a disk with a smaller disk, so you would have to shrink the array by removing the disk and rebuilding parity, then add the smaller disk. If that is what you want to do then shut down, check connections, and proceed to copy the data from that disk to others.

 

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Ah fine, yes I wasn't meaning that I would never have to back up anything more going with that the level of raid would mean this disposable data was more resilience, so that is fine.

 

I am currently running my `cp` command when the array is alive, should i turn this off?

 

- Edit:

 

I took the array offlline, un assigned Disk 1.

 

I have now mounted Disk 1 and am moving the data from that to Disk2. To clarify, when finished I need to:

 

- Shut down

- Remove Disk 1

- Rebuild Parity (Not 100% sure how to do that just yet)

- Shut down

- Add replacement Disk

- Start up.

Edited by runtman
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Just a question for when this data copy is finished, I will unmount and remove this disk how do I actually rebuild parity at the moment it just lists this disk at "missing" do I need to make a new config? I'm afraid at losing my data here.

Edited by runtman
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Eeek, so what should I do in this case? I can either fit a replacement drive (1TB) or just remove the bad drive (2TB). I don't have a spare 2TB currently. I have plenty of space in the array for this.

 

Is it just a case of ordering a replacement 2TB and allowing the cluster to be 1 disk down for a time period?

 

Thank you for all of your help

Edited by runtman
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4 minutes ago, runtman said:

So it's a case of stopping the array, taking the disk out, applying a new config and starting the array again? Are there any special options I need to click so I don't lose data?

Just make sure you don't assign a data disk to the parity slot. You can change the other assignments if you want.

 

DON'T check the parity valid box, since you need to rebuild parity.

 

Also, it shouldn't happen, but just in case, DON'T agree to FORMAT anything.

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