Jump to content

I killed my data at disc rebuild, how to do it correctly ?


Recommended Posts

A disc died and I tried to rebuild the data with help of a used spare disc that was around.

The "new" disc had already partitions and some old data on it (not related to the nas).


So I followed https://wiki.unraid.net/Replacing_a_Data_Drive and at the "Assign the new drive in the slot of the old drive" it complained that the disc is too small.

So I wiped the new disc with

sgdisk --zap-all /dev/sdX


Afterwards, if I remember correctly, it formatted the new disc. I was able to use it with the unassigned plugin.


So afterwards I was able to add it at the "Assign the new drive in the slot of the old drive" step.

Likewise it showed the popup that I "ignored" because I did not formatted any disc and was not aware that I format anything unmountable.




So I ended up with a empty disc with complete data loss, realised it a week later so my memory is a bit fuzzy.

I google a bit what could gone wrong and immediately found that this is a common Unraid problem (seriously wtf).


At the next disc fail I would likely do it similar again.

I did in the past at several different NAS vendors (Synology, Qnap, some HW Raid) and never had a problem because the way to do it was crystal clear and self explained.

So what is the correct way if it complains for some reason like disc to small due old data on it? 

That is not covered by the docs and acting with common sense leads to data loss.


Tbh I did not expect that Unraid tries to delete my files so I gave it not too much attention because I expected it just works like at all other NAS Software I used in the past. 

Link to comment

When you replace a disk there is no format step involved, so it is not clear from your description what really happened,


The link link you gave is not to the official documentation accessible  via the ‘Manual’ link at the bottom of the Unraid GUI - the correct link is this one, but whether it would have made any difference I have no idea,


Link to comment
On 10/4/2021 at 10:32 PM, itimpi said:

When you replace a disk there is no format step involved

yea but if I try that it complains that the disc is too small because there are already partitions or something on it - rebuild doesn't work then


On 10/4/2021 at 10:32 PM, itimpi said:

The link link you gave is not to the official documentation accessible

Oh thats read a bit different to the other docs ... not sure why there is a very incomplete doc online at the official Unraid site that is google search hit number one.

Who expects that incomplete docs are presented at the main unraid site.


Normally I would would expect that you don't need such docs, but in unraids case the devs decided to make the rebuild function not bullet proof - so additionally your data depends on it which doc you actually read .... 


Sorry if this reads like a rant, but I really didn't thought that the rebuild process at unraid is so shaky and user-unfriendly designed :(

The two different docs are just the icing on the cake, really.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...