Unformatted disk after data rebuild

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I would like to save files if possible. I have all 3 original disks. I'm not sure which disk is which, or what data is on them. O whether it was the original 13. I was hoping there was a way to read software raid configuration data from the drive. It could be the original 10 or 11 or wiped and re-formatted already. I only saw a folder structure. I have 2 other disks I haven't tried browsing yet.


I guess it's the array being out of sync I'm sort of trying to figure out. It seems like I added a disk to the array, and instead of copying files it just added blank space to the array. So I wanted to try to assess what is on my disks first, maybe get them labeled and organized with the hope it would add the lost data somehow. In other words, I think I added a disk incorrectly and blanked the file system out during the rebuild. But I also think the original red balled disk wasn't actually bad, so I was exploring the possibility of re-syncing the array to the original disk.

Edited by dogfluffy
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Of course you would like to save files if possible. That isn't my question. We hope to save as much as possible. But if there is anything you know is important and irreplaceable, then before doing anything else, you should try to copy that data to another system in case anything goes wrong. You must always have a backup of anything you truly don't want to lose.

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I don't know how I could back up 42 TB, and I don't know what is missing because of the way Unraid spans across the disks. I don't have a comprehensive backup, sorry. Only what is stored on these disks, and now I have 2 'extra' disks for swapping or recovering data as necessary. So I am hoping the backup is stored on a disk and I can re-sync the array.

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On 8/31/2017 at 7:20 AM, trurl said:

I think johnnie.black has a good plan for starters. Rebuild disk13 to a new disk. Then we can go on to possibly fixing that rebuild if necessary, and seeing what can be done with the old disk11 and old disk13.

I am bringing this forward to the new page because I think it is still the plan.

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5 minutes ago, dogfluffy said:

I don't know what is missing because of the way Unraid spans across the disks.

You don't need to know which disks a file is on. You just need to know which user share(s) your important and irreplaceable files are on. For example, do you have any baby pictures or something like that? Do you know which user share you would have stored them in?

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1 minute ago, dogfluffy said:

Is there someone who can answer my questions regarding trying to ID these disks before I start adding unknown things to the array? I thought my lesson, beyond backups, was to stop and gather info before proceeding. I'd like to try to figure out if this is possible first.

What is your question exactly? Unraid identifies the disks by their serial numbers. It associates the serial number with the assigned disk slot. What other ID could you be talking about? And why are you talking about adding anything to the array?

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I'm sitting here with 3 disks, none of which are currently added to the array. They all have been previously, at some point. I would like to attempt to ID these disks, to find their original spot in the array, if possible. It would need to be off the data contained on them, serial numbers won't help to ID where they previously had been installed. Like if it had a configuration file unraid reads to assign them as disk 10 for example. Knowing the serial number of current 10 is useless to me.


The data set is too massive to do it the way you suggest. I can't possibly find what is missing from 42 TB. The best I can hope is to figure out what 3 puzzle pieces of data these disks do contain, then if I can ID them back to the original slot and sync in time with the unraid array...that would  be ideal. I have to work backwards to do it. Meaning if my Spare1 contains X data, Spare 2 contains Y data and Spare 3 Z data, then array once started is missing Y data but has Z data...I at least know I can blank out the Z drive and recover the Y data later. I have an unknown missing data set right now, and 3 unknown disks. I also have a "hole" in my array containing a blank disk, as well as some sort of sync issue. 

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Reviewing the thread, you mention raid a couple of times in such a way that it makes me wonder if you understand that Unraid is not RAID, not even a software RAID. Each data disk is independent and can be read without any of the other disks. The thing that makes Unraid RAID-like is parity. There is a separate parity disk which allows the bits of a missing disk to be calculated from the bits on the parity disk plus all the bits on all the other disks.


The only thing that specifies where in the array a disk belongs is the config/super.dat file on the flash drive. It has a record of the current assignments by serial number.


Those "spare" disks, if they have data on them, can be read independently of the array. You can get the array going again without those disks, then see what is on them later.

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Past my bedtime. Review the thread and see if anything makes more sense to you and what questions you still have. We can get into the specifics of how to proceed tomorrow. I will just give a quick overview here in case anyone wants to comment on it or has any other ideas.


Rebuild disk13 to a new disk.

Check and repair the filesystems on disk10 and the rebuilt disk13.

Try to mount whatever other disks are still available outside the array and see what's on them.


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OK great. I am completely lost, although I think I followed your explanation. I was concerned if I add this disk 13, that during the rebuild it might blank the data already on it. I suppose I need to try and index these disks as best I can to piece together what I have first. Then I can try to read the existing unraid drives, find the missing data to make sure it's preserved and added later. I had been thinking I could find and add the original disk back into the array, as opposed to just copying the data back afterward.


I figured out how to mount and browse these in the Umenu file browser outside the array. I have 2 spare disks with data, the one installed in the case and ready to assign #13 has data. Another spare is blank. Another spare has different data than the first it appears at cursory glance. I think as long as starting with this disk installed doesn't delete anything, I found my missing data set...hopefully.

Then I just need to make disk 10 browseable and copy to the blank disk I believe right?


So basically what you were saying about adding the disk 13 wouldn't be destructive. I added a blank disk and it remained blank? I'm only confused about the parity being out of sync now, since I don't know what it missing once the array starts up. Thanks for all your help and I'll tackle this with fresh eyes in the morning. I guess I should unassign the blank disk to try to mount it, then re-assign it afterward.

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OK I think I am very nearly up to speed with how this works, finally. Luckily you didn't run out of clubs to beat it into me with!


So I couldn't mount or even file system check disk 10, basically says it's missing a superblock. I also believe I found the missing disk 10, labeled it and set it aside. It sounds like the only real question is whether to shut down and yank the assigned WDC disk 10, replace it with my labeled spare disk 10 and restart with this disk 13, once it's back added to the array. Maybe a question of sequence, or just use the one installed in the case already and copy the spare drive data after it rebuilds and adds a superblock? Anyway...I think I have a handle on my chaos now. I might print up some fancy numbers to mark these for easy access in the morning before I put this all back to sleep. Thanks for all the help, I was misunderstanding how it worked and you cleared that up nicely.

Edited by dogfluffy
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Let's just concentrate on a single disk at a time. That is the way you have to work with Unraid anyway.


Let's not talk of "adding" anything. One possible (preferred) meaning of the word "add" in the context of Unraid is when we are talking about adding a new disk to a new data slot to expand the array. This is definitely not anything to be considered at this point. Unraid won't even let you expand the array when you already have a disabled disk in the array.


"Removing" is another word like that. One possible (preferred) meaning of remove is removing (but not replacing) a disk from the array to shrink the array. Also not something to be considered at this point.


"Replacing" is when you replace a disk in the array and let Unraid rebuild the contents from the parity calculation. When you replace a disk, you assign a different (usually new) disk to the same slot the (old) disk was using. Then when you start the array, Unraid will read parity and all the other disks to calculate the data to write to the replacement.


Currently, you have a disabled disk13. I am proposing replacing disk13 with a different (preferably new) disk and letting Unraid rebuild disk13 onto the replacement disk. Obviously you must use a disk for the replacement that doesn't have any data on it (that you care about) because it will be completely overwritten by the rebuild.


Then we can concentrate on the next thing.



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Ok gotcha. Yes, the terminology makes explaining this a bit complicated. So I do need to pull my case installed disk13 with data on it and replace it with the blank "disk 13" then assign it and start the array so it can rebuild. 


I believe I'm up to speed now, except for understanding the parity right now. Meaning how do I figure what "parity" will do to disk 13 before it happens? You seem to know it will start formatting and disk13 will be erased and wind up blank, and I don't understand why exactly. It might be academic however, if I swap these disks and replace 13 and 10, I still think I have the data that used to exist in parity on the original disks 13 and 10. I suppose this highlights my misunderstanding because I would have thought a 13 with data would simply replace to the back to the parity drive with no data loss or formatting.  It's a little confusing what holds the master record of files or parity. I've got work to do and I'm going to try and label and organize these for the future. Thanks.




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20 minutes ago, dogfluffy said:

You seem to know it will start formatting and disk13 will be erased and wind up blank

Rebuild doesn't format anything. I think I already said format is NEVER part of the rebuild process. But you did mention formatting a disk in the very first post in this thread. Looks like it must have been disk11 since it seems to be empty.


The screenshot you posted with the array started seems to indicate the emulated disk13 isn't empty. So I don't expect it will wind up blank and I don't know where you got that idea.


You have used the word swap in the same sentence with 2 disks, but I assume you don't mean swap them with each other. This is very confusing. Let's just concentrate on one thing at at time. We are only talking about replacing disk13. I don't know if there is any reason to replace disk10, and there is no reason to think about disk10 right now.


And you talk about parity as if it has data on it. It doesn't. That is not how it works.


I don't know whether to try to explain how this all works or just tell you what to do. There is a lot about all this that you clearly don't understand.


In any case, DON'T do anything at all except what we tell you to do. Don't even think about the next step until the current step is complete. If you are unsure what you have been told to do then ask for further explanation.


If you want to label and organize the disks that are not currently installed then that is OK though I am not sure you know what is on them anyway. Don't do anything with the server except as instructed.


I will see if I can include some explanations as we go. Let's just concentrate on one thing at a time. You have already started talking about the other disks again.


This post is mostly a response to your posts. Don't take it as instruction to do anything at all. I will start another post about what to do. I may even try to explain a few more things before I give you the first instruction.


We will probably be at this for a few more days and pages.



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I already swapped the disk 13 for the blank disk and added it to the array so it is rebuilding now. You said during the rebuild of disk 13 the data would be formatted off or wiped. 


I don't understand what is the difference between emulated and the original. I have both original disks 10 and 13...I believe. I at least have 2 disks with data on them and 2 that are blank and now both added to the array. Disk 10 is added but still unformatted file system.

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30 minutes ago, dogfluffy said:

You said during the rebuild of disk 13 the data would be formatted off or wiped. 

Please show me exactly where I or anybody else said this. This can only be your misunderstanding of what we said. Maybe this is what you are referring to:

2 hours ago, trurl said:

it will be completely overwritten by the rebuild.

I never used the word format, or even wipe. "Format" actually has a very specific meaning and many people don't know what that meaning is. That often gets them into trouble here. "Wipe" on the other hand doesn't really have a clear meaning so I will let that go.


When I said it will be overwritten, all of its bits will be replaced with the bits from the parity calculation. Ideally, that will result in all of the data being reconstructed, but that ideal may be compromised by other things. Users doing the wrong thing such as formatting, for example.


The emulated disk is the data that results from using the parity calculation to access the disks data instead of actually accessing the disk. Unraid disables a disk when a write to it fails. After Unraid disables a disk, it won't try to access the disk again until it is rebuilt, since its contents are no longer valid. Instead, it reads parity plus all of the other disks to calculate the data for the disk.

36 minutes ago, dogfluffy said:

I already swapped the disk 13 for the blank disk and added it to the array so it is rebuilding now.

There is that word "added" again.


Do you mean you "replaced" disk13 with a blank disk? And assigned that blank disk to the disk13 slot? I hope that is what you mean.

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Yes it's terminology. When I say formatted or wiped, I mean I would suffer data loss on the disk during the data rebuild.


I will have to see what gets written to disk 13 after the rebuild. I have an empty disk 11 and an unformatted disk 10, also empty. I have 2 disks with data, hopefully matching.

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15 minutes ago, dogfluffy said:

I have an empty disk 11 and an unformatted disk 10, also empty. I have 2 disks with data, hopefully matching.

I suspect you formatted disk11 as already mentioned, but I don't remember if we have some reason to suspect disk10 is empty. Did you already try repairing it?

On 8/30/2017 at 4:48 PM, johnnie.black said:

He can also try running reiserfsck on disk10.

But let's not get ahead of ourselves and wait on the rebuild.



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No, I don't believe I ran reiserfsck on disk10...but I can't be certain. Yesterday I did unassign disk10, then in unMENU I mounted and tried to browse it, which showed blank. I re-assigned disk10 before assigning disk13 and rebuilding this morning. I'm not sure I'm using the optimal method to try and view files. I was wondering whether you can view what files are on the parity drive or whether it's just abstract data.

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