[Solved] Readding removed drives unraid V6.7.2

[pete69]

I am new to unraid so trying a few things to see how it all works before moving my data across.

 

I am using an old HP 380DL G7 with 8 147gb SAS drives for the testing.

 

Install went well, I set up 2 of the drives as parity drives and the rest as storage.

 

I wanted to test a 2 drive failure, so removed 2 drives.

 

This seemed to work with the data being emulated at first.

 

Then I did a parity rebuild which also worked correctly.

 

-1st question: during the parity rebuild, I assume there is no protection if another drive fails as we are already rebuilding from 2 drives?

-2nd question: what if only a single drive failed and I started a parity rebuild, is the array safe from another drive failing due to having 2 parity drives, or am I in the same position as Q1 since both parity drives are being rewritten, there is no protection from a 2nd drive failing while the rebuild takes place?

 

So now I wanted to move on, and re-add the 2 drives I removed back to the array, but unraid did not see them, it just shows "Not installed" on the Main page.

 

The disks were labeled as Disk 5 & 6 in my case. Even though they were not showing as installed I could click on the disks and see their settings.

 

They also do not appear in unassigned devices.

 

Stopping and restarting the array made no difference, nor did restarting the server.

 

 

If I look at tools>system Devices, it showed all 8 disks in the SCSI Devices list.

 

Reading through various threads it seemed I might need to re-define the array.

 

I did a Tools>New Config and Preserve current assignment for all.

 

This shank the array to just 6 disks showing out of the 8.

 

I rebuit the parity again after the new config and the 6 drives are fine, but I still can't find a way to add the 2 removed drives back to the array.

 

now on the main page Disk 5 & 6 are just showing as unassigned, but there is no option to assign them in the drop down.

 

 

If I look at tools>system Devices, it now only shows 6 of the 8 disks in the SCSI Devices list.

 

HP bois shows all 8 drives

 

Q3: Any suggestions?

 

Thanks,

 

Pete.

 

PS I don't have any other sas drives to test if the problem is just with the serials of the 2 I removed.

unraid1-diagnostics-20190817-0630.zip

Edited August 17, 2019 by pete69
Solved

[trurl]

6 hours ago, pete69 said:

1st question: during the parity rebuild, I assume there is no protection if another drive fails as we are already rebuilding from 2 drives?

That is basically correct, except I would reword it a little since the way you have it I think may indicate a misunderstanding. It is not rebuilding FROM 2 drives. It is rebuilding 2 drives FROM all the others. Dual parity allows you to rebuild up to 2 drives simultaneously.

 

6 hours ago, pete69 said:

2nd question: what if only a single drive failed and I started a parity rebuild, is the array safe from another drive failing due to having 2 parity drives, or am I in the same position as Q1 since both parity drives are being rewritten, there is no protection from a 2nd drive failing while the rebuild takes place?

And this is similarly worded wrong and probably indicates you misunderstand.

 

It isn't rewriting both parity drives, or indeed any parity drives, unless the single failed drive is itself a parity drive. It is only writing to the drive that is rebuilding. If you have dual parity, then if you have a single failed drive, all the others still have parity protection.

 

After that you begin to make mistakes.

 

I'm not entirely sure what you meant about not seeing the disks. Maybe you just needed to stop the array and reassign them. Or maybe there is a problem with the controller you are using. I see it is mangling the disk serial numbers, so it is probably not really a good controller to be using with Unraid.

 

After you did the New Config without the disks, and rebuilt parity, there is no longer any way to rebuild the disks you removed. And you don't want to add them as new disks now because Unraid would clear them. You will have to New Config and rebuild parity again.

 

But I don't see any other disks in the Diagnostics, so if they are indeed attached, I suspect something going on with the controller.

 

I'm not sure where to go from here. Can you tell us more about the controller? I will ping @johnnie.black since he knows more about controllers than I do.

[pete69]

Hi Thanks for the reply.

 

I wasn't expecting to access the data on the removed drives when I reinstalled them after the rebuild, I just wanted to add them back as new drives to expand the the array again.

 

But unraid was not allowing them to be added, even though the settings data was still showing for those drives in unraid.

 

With the array stopped the option to assign was not available on these drives.

 

The issue turned out to be the internal HP P410i raid controller tagging these drives as bad after I removed and re instated them a couple of times, even though it is running in HBA mode.

 

Thanks for answering the 2 questions though. 

 

As I understand it, in this case the parity rebuild wouldn't have been rebuilding 2 drives, as the drives had been removed without replacements. It would be rebuilding parity across the entire array with the remaining drives so that 2 drive redunancy is mantained with 2 fewer drives?

[trurl]

38 minutes ago, pete69 said:

As I understand it, in this case the parity rebuild wouldn't have been rebuilding 2 drives, as the drives had been removed without replacements. It would be rebuilding parity across the entire array with the remaining drives so that 2 drive redunancy is mantained with 2 fewer drives?

I assume the case you are speaking of is New Config. Rebuilding parity is what New Config does by default. There is no way to get Unraid to rebuild data disks with New Config even if you had replaced them.