UNRAID Drive Failure Advice

[ChrisLoudon]

Hi guys,

 

One of my 4TB drives in  my UNRAID array as moved from having a single SMART error that I've been nursing for a while now with no issues however, a couple of days ago I started getting more errors so now I want to look at getting the data off that drive.

 

While I could go ahead and buy an new drive and go through the steps of rebuilding the data from parity, I've got plenty of space on the other drives so wanted to know how to shift / reallocate the data currently stored on the failing drive onto the other drives.

 

My intention would be to empty the faulty drive then just remove it from the array.

 

Thx

[porina]

I have wondered the same before and looked up guides. Unfortunately they don't seem to have a one button script to do it. There are a multiple versions of ways to do this you can look up and try. Some preserve parity, some don't so require a rebuild. I never did it in the end because I thought the risk of me making a mistake and losing data was not worth it. I'm just waiting for a specific drive to be at the right price before I wholesale replace a bunch. It might just be easier to get a replacement drive as swapping and rebuilding is easy.

[OddOod]

There is a plugin called unBALANCE which will level the distribution in your array

[ChrisLoudon]

5 minutes ago, OddOod said:

There is a plugin called unBALANCE which will level the distribution in your array

Thanks buddy,

 

I've just found unBALANCE now and it looks like it does what I need.

 

The only issue I'm finding with it is its doesn't appear to 'Scatter' all the data on the source drive to all other drives even if there's enough space.

 

Unless I'm missing something, I'm currently selecting xyzTB of data then moving it to a single drive with at least that free. Once that drive fills up, I repeat with another selection of folders and move them to the next drive. Rinse and repeat!

 

Anyhoo, this seems to be working and Parity appears to be rewriting as this progresses so fingers crossed I'll have everything off this drive by tomorrow and I just remove the offending drive from the array. 

[OddOod]

13 minutes ago, ChrisLoudon said:

The only issue I'm finding with it is its doesn't appear to 'Scatter' all the data on the source drive to all other drives even if there's enough space.

 

I think you want this section of the unraid docs
https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array-configuration/#removing-data-disks

[ChrisLoudon]

5 minutes ago, OddOod said:

I think you want this section of the unraid docs
https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array-configuration/#removing-data-disks

Thanks.

 

I did a bit of Googling earlier on this.

 

Am I right or wrong in thinking, a parity rebuild after a drive has been removed due to failure requires another new drive to be installed in its place?

 

I think that's what Google was telling me so that's why I'm just moving the data and allowing parity to be rewritten so I don't need to fork out for another drive.

 

I'm sure someone on Reddit had asked a similar question in the hope he could just yoink the offending drive, do a parity rebuild and have it redistribute the recovered data across the remaining drives but the answer appeared to be no.

[OddOod]

13 minutes ago, ChrisLoudon said:

Am I right or wrong in thinking, a parity rebuild after a drive has been removed due to failure requires another new drive to be installed in its place?

You are correct. But if you follow the steps they lay out, step 4 will let the system know that it needs to rebuild parity ignoring that drive

[porina]

15 hours ago, OddOod said:

I think you want this section of the unraid docs
https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array-configuration/#removing-data-disks

Looking at that again reminds me why I didn't go ahead with my own disk removal. That standard process leaves you without parity until you rebuild it. The advanced parity preserving method, if you make a typo things can go bad fast.

 

14 hours ago, ChrisLoudon said:

Am I right or wrong in thinking, a parity rebuild after a drive has been removed due to failure requires another new drive to be installed in its place?

If you replace the drive, you're rebuilding the data on the replaced drive, not rebuilding parity information itself.

If you don't replace the drive, you need to rebuild the parity data unless you zero'd the outgoing drive while it was in the array to keep the parity data correct.

 

14 hours ago, ChrisLoudon said:

I'm sure someone on Reddit had asked a similar question in the hope he could just yoink the offending drive, do a parity rebuild and have it redistribute the recovered data across the remaining drives but the answer appeared to be no.

In theory it might not be impossible, but it would be complicated to implement and risky. Better to do the existing documented methods.

 

Think about the steps involved. You'd still have to create the virtual failed drive using parity data and remaining drive data. Then you move data off that virtual disk onto real disks, updating parity as you go. Only when you've moved all data off, you can zero out the virtual disk and remove it.