My setup has two 2Tb parity drives.

One of them failed, and I was left with a single parity drive and an emulated drive, 'Disk 1'. I installed a new replacement drive, following the advice in https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array/replacing-disks-in-array/. However, I encountered a problem where in the advice it says "If you started in Maintenance Mode, go to the Main tab and manually click Sync to start the data rebuild." I couldn't find anything at all that said 'Sync' in the Main tab under Maintenance Mode. I clicked on something which seemed similar and the parity process started. It took about 24 hours to complete. Then I rebooted, everything came up correctly, but Disk 1 is still there with its little X next to it.

According to the Shares tab my data is still there (and it also shows up with the little blue box icon before Disk 1). It is listed as being held in 'Array'. Has it transferred to the two Parity disks or is it still being held in the 'emulation' in Disk 1? I also can't understand why Disk 1 shows the FS as being ntfs.

I have a suspicion that all is not well and that my data is at risk. How do I make sure the data is being held properly on the two Parity disks and how do I then get rid of 'Disk 1'?

There is probably an answer to this, but I have done a lot of searching and nothing promising has shown up. I may be using the wrong terminology. Anyway, any help is much appreciated.

Why are you using NTFS for an array disk?

Attach Diagnostics ZIP to your NEXT post in this thread.

I am puzzled by the 'ntfs' as I said in my post. I thought the parity drives had their own formatting standard?

Anyway, here is the diagnostics file.

thinkcentre-diagnostics-20260824-1436.zip

The ‘little blue box’ is standard. You click on it to initiate File Manager.

1 hour ago, stokeymj said:

am puzzled by the 'ntfs' as I said in my post.

The NTFS question still applies - it is the file system you have set for the emulated disk1.

1 hour ago, stokeymj said:

I thought the parity drives had their own formatting standard?

Parity drives have no file system.

Not sure what you did originally but disk1 is still being emulated so needs rebuilding to make it active again.. However since it is in NTFS format ideally you would copy it s contents elsewhere before rebuilding disk1 and copy the data back afterwards once it is formatted to a Linux style file system (probably want Xfs).

Not sure why you have 2 parity drives protecting a single data drive. You may be better off using one of them as an additional data drive instead.

Was disk1 originally in a Windows system?

You really need to start over with a new array, but we can still save that emulated NTFS data before your do.

I don't see any disk being assigned as the new disk1 in syslog. It looks like you may have assigned or reassigned parity2, and it is the disk that was rebuilding.

I don't see any disk that might be assigned as the new disk1 in your SMART reports either. Is that disk still attached?

Is your parity disk SSD?

I am sorry, I’m used to dealing with disks on a Linux system, but I feel somewhat out of my depth dealing with Parity disks, arrays and the like.

To try to answer your questions, one of the parity disks is SSD and the other is a regular disk. The failed disk was originally ntfs, but I thought it had been reformatted. Maybe when I first set it up, this disk was just a data disk and the SSD was the parity disk.

I can connect another drive and copy the data from Disk1to it. I’m not sure exactly how to do this, but I can figure it out. Then I can rebuild the array, as you suggest. Maybe I should use the hard disk for the array and use the SSD as a data disk?

Your help is very much appreciated.

A question: does a basic array consist of a data disk plus a parity disk? I think I have become confused about the difference between an array and parity.

Just now, stokeymj said:

A question: does a basic array consist of a data disk plus a parity disk? I think I have become confused about the difference between an array and parity.

The parity disk(s) are optional in the array depending on if you want protection against disks failing., but you must have data disk(s).

How can I copy data from Disk 1 if it’s an emulation and it’s not mounted? Sorry, have just discovered the copy function.

Edited August 24Aug 24 by stokeymj

3 hours ago, stokeymj said:

How can I copy data from Disk 1 if it’s an emulation and it’s not mounted? Sorry, have just discovered the copy function.

What makes you think the emulated disk is not being mounted? Both your screenshot and the earlier diagnostics show it mounted with about 12% of it containing data. The whole point of Unraid’s emulation feature is to allow the system to operate as though a failed/missing disk is actually present.

I don't recommend putting SSD as parity or data in the array. SSDs in the array cannot be trimmed, and can only be written at parity speed. SSDs are better in pools outside the array.

You definitely don't need 2 parity disks. 1 HDD parity should be good enough for several array data disks.

You didn't answer this question:

9 hours ago, trurl said:

I don't see any disk that might be assigned as the new disk1 in your SMART reports either. Is that disk still attached?

Your reply re the SSDs, HHDs and parity are much appreciated. I do remember seeing a reference to that in the documentation, but it had slipped my mind.

Your question about the lack of a disk to be assigned as Disk 1: what is now the second Parity disk was supposed to do that. I think I now need to stop the array, remove that second parity disk, re-format it, and then reinstall it as a new data disk. Is that correct? Should I copy the emulated disk files onto a separate drive first, or can I copy after the drive is re-formatted and reinstalled?

22 minutes ago, stokeymj said:

what is now the second Parity disk was supposed to do that. I think I now need to stop the array, remove that second parity disk, re-format it, and then reinstall it as a new data disk.

Order slightly wrong. Add it as an additional data disk,; let Unraid ‘clear’ it; and when clear completes you can format it. Formatting it before adding it is pointless as Unraid will still ‘clear’ it.

23 minutes ago, stokeymj said:

Is that correct? Should I copy the emulated disk files onto a separate drive first, or can I copy after the drive is re-formatted and reinstalled?

You can copy the emulated drive contents onto the newly installed data disk once it has been formatted as an alternative to copying it to a drive external to the array.

9 minutes ago, itimpi said:

Order slightly wrong. Add it as an additional data disk,; let Unraid ‘clear’ it; and when clear completes you can format it.

You can copy the emulated drive contents onto the newly installed data disk once it has been formatted as an alternative to copying it to a drive external to the array.

I think this is where I went wrong the first time. I have stopped the array. The system does not seem to give me any options regarding the array. The dropdown menu for Parity 2 allows me to choose 'no device'. The dropdown menu for Disk 1 doesn't give any options. I can't see anything which allows me to add to, remove from or modify the array. How do I "Add it as an additional data disk."? Am I working with the wrong part of the UI? The next section down, Pool Devices, allows 'Add pool' but there is nothing like this under Array. Sorry to be so slow on this.

I think I have sorted it out. I needed to select 'no device' for Parity 2, which freed up the drive to be allocated to Data 1.

Thanks for your patience.

Still not working! Now it says 'missing disk' for Parity 2 and will not allow the array to re-start. How do I tell it that I no longer want a Parity 2 drive?

1 hour ago, stokeymj said:

Still not working! Now it says 'missing disk' for Parity 2 and will not allow the array to re-start. How do I tell it that I no longer want a Parity 2 drive?

When you set parity2 to not assigned did you not have a checkbox that needed ticking to allow you start the array without parity2?

1 hour ago, itimpi said:

When you set parity2 to not assigned did you not have a checkbox that needed ticking to allow you start the array without parity2?

No, I didn't see any checkbox. Would it be in the same area or would it be further down the page under array management?

8 minutes ago, stokeymj said:

No, I didn't see any checkbox. Would it be in the same area or would it be further down the page under array management?

It would be further down the page near to the button for starting the array.

If you assign a disk as disk1, it will rebuild onto that disk. The rebuild will result in the same NTFS filesystem you already have with the emulated disk. Better to assign it as disk2, let it clear, format it, then copy the contents of the emulated disk to it. Then you can New Config/Trust Parity to get it reassigned as disk1 if you want.

thinkcentre-diagnostics-20260828-0836.zipThis seems to have lost the text I had composed to go with it!

Basically, I have been following your advice, but the process has been a lengthy one. I have copied the data from the emulated disk (Disk 1) to a new disk (Disk 2). However, the process never seems to complete. The bottom of the Main screen on the UI tells me: Array Started Completed: 99%,  Speed: 1.82MB/s,  ETA: 33:41:21. I don't know what this means, and I am hesitant to stop the array in case it fouls up the copying process which has already taken something like 36 hours! I need to stop the array to follow the next bit of your advice about reassigning Disk 2 and Disk 1.

Edited August 28Aug 28 by stokeymj
My original accompanying text seems to have got lost from the original post.

Oh, and I also apologised for keeping on coming back with queries. I really want to complete the process you have suggested so that I can mark this thread as 'solved'.

Edited August 28Aug 28 by stokeymj

On 8/25/2026 at 4:14 PM, trurl said:

If you assign a disk as disk1, it will rebuild onto that disk. The rebuild will result in the same NTFS filesystem you already have with the emulated disk. Better to assign it as disk2, let it clear, format it, then copy the contents of the emulated disk to it. Then you can New Config/Trust Parity to get it reassigned as disk1 if you want.

OK. I have reached the point of trying to reassign Disk 2 as Disk 1. In New Config I don't seem to have anything that says 'Trust Parity' as per your suggestion. How do I achieve the disk reassignment, and will all the Shares then point to the correct places on the new disk?

Edited August 28Aug 28 by stokeymj

Actually you don't want to trust parity since you will be removing a disk. Post a screenshot of your disk assignments.