Broke flash drive, restoring old backup, unknown disk order

[Alex84]

Hi all,

 

unfortunately, I broke my flash drive and realized I only have a backup with an outdated disk assignment.

Recovered the backup, replaced the key 

 

My parity was assigned correctly as were 2 of the other 5 hdds.

The 3 remaining drives cannot be assigned. 

 

Following the wiki [1], I was asked to reach out to the community for help: 

 

Quote

If you do not know which disks were assigned where, create a post in the forum for further assistance.

 

Help is highly appreciated.

 

Kind regards,

Alex

 

[1] https://wiki.unraid.net/UnRAID_6/Changing_The_Flash_Device

[trurl]

If you are absolutely sure about parity then it doesn't matter. The way you can lose data in this situation is by assigning a data disk to the parity slot. 

 

Please keep your Flash backup current!

[Alex84]

Hi trurl,

 

thank you for the quick reply. Yes, lesson learned. Did a backup before assigning new disks last time. Did not do any other after everything worked...

 

How can I be sure about the partiy drive? I only noticed, that the parity was automatically detected and assigned after recovering the old backup. The only thing manually changed was the key file which was replaced.

[JonathanM]

13 minutes ago, Alex84 said:

I only noticed, that the parity was automatically detected and assigned after recovering the old backup. The only thing manually changed was the key file which was replaced.

That only means that the physical drive that was assigned to parity at the time the backup was taken was found. Doesn't mean that drive was your parity drive currently.

 

However... if that drive is the only 2TB drive and all the others are 1TB, it must be parity.

 

What sizes are all your drives that were in the array when the USB died?

[Alex84]

I see. The 3 available but unassigned / not matching drives are 1TB each, so it seems the parity disc is correctly identified.

When you say "then it doesnt matter", do you imply that I could assign the 3 discs in any order and Unraid would make sense of them after starting the array?

 

My server is running on Unraid 6.5.3

[trurl]

6 hours ago, Alex84 said:

I could assign the 3 discs in any order and Unraid would make sense of them after starting the array?

Yes.

 

You will still have your user shares, because the user shares are just the top level folders on all disks. But you won't have any of the settings you made for those user shares, so they will all have default settings.

 

You also won't have any of your other settings, so you would have to do them all again. If you had any dockers then you won't have any of their templates, but if you can set them up again exactly as they were then their appdata should be fine since that is on your disks.

 

6 hours ago, Alex84 said:

My server is running on Unraid 6.5.3

You should upgrade. Lots of things better now. And we can support you better.

 

 

 

[trurl]

Did you have cache disk(s)?

[Alex84]

No cache drive involved. Thank you for the detailed answer. (This may be worth a FAQ) 

Will start the array later today with all 12 fingers crossed

 

Edited February 24, 2020 by Alex84

[trurl]

If it offers to format anything, DON'T

[Alex84]

OK thanks for the warning.

In the meantime, I figured out I did report something wrong.. The 3 missing drives are 1TB each. But the 3 suggested drives are 3 TB each. This really confuses me as I cannot exactly recall the last changes I did to the array. 

 

While I m pretty sure that the 2TB is still the parity (yes that would mean that the 3TB drives only used 2TB of its capacity so far), is there any other option to verify the parity drive? Any comand I could run?

 

 

Also found this post: 

 

Quote

As long as all your drives are error free, it's no big deal. Just assign ALL the drives to data slots, MAKE SURE THERE IS NO PARITY DRIVE ASSIGNED, and start the array. All the data drives should mount just fine, and be browsable.  There should be one drive that shows unformatted, that's your parity disk. Make a note of which drive should go where, stop the array, set a new config (with 4.7 it's a command line thing) and assign all the drives to the correct slots, being very sure which is the parity drive. Start the array, and it will recalculate parity and write it to the drive that you assigned.

Is this also correct for 6.5.3? 

So to validate that the parity is infact the parity, I would assign all data discs and unassign the parity. Then starting the array, getting confirmation that there is NO drive reported as "unformatted". If thats the case I can reassign the parity, starting again, waiting for a full parity rebuild? 

I just dont get the part with the "set a new config"

Edited February 25, 2020 by Alex84

[JonathanM]

1 hour ago, Alex84 said:

While I m pretty sure that the 2TB is still the parity (yes that would mean that the 3TB drives only used 2TB of its capacity so far),

If there are 3TB drives in the parity array, one of them MUST be the parity, which means the 2TB assigned to parity in your first screenshot is really a data drive, not parity. Unraid will not allow a smaller drive to be assigned as parity.

 

Go to Tools, New Config, preserve none, then go back to the Main tab and assign all the drives as data drives, DO NOT POPULATE either of the 2 parity slots, they must say unassigned.

[Alex84]

Worked perfectly. Let me summarize for the future generation: 

 

1. Find parity drive: Create new config (preserve none) -> start array with all drives assigned as data drives -> one 3TB drive showed up as "unformatted"

2. Fix drive assignment: Stopped array -> new config (again) -> assigned all data drives as datadrive, assigned identified parity drive as parity

3. Rebuild parity: start array -> rebuild parity starts automatically

 

thanks for the quick support!

[trurl]

3 hours ago, Alex84 said:

Worked perfectly.

👍

 

On 2/23/2020 at 10:18 AM, Alex84 said:

My server is running on Unraid 6.5.3

Please upgrade

[Alex84]

6 hours ago, trurl said:

Please upgrade

First the parity rebuild, then a quick backup of the flash drive, next is the share config which got lost in the process

Once all is done, I will upgrade for sure.  

 

[trurl]

Just thought I would add another cautionary note to all this.

 

Another way people have lost data in this situation is by using a flash backup that isn't current. Here is how this happens.

 

Sometime after making a flash backup, you assign a new parity disk. Then, you add that old parity disk as a new data disk.

 

Later, you need to use the flash backup, but it still thinks that new data disk is parity. And you have the array set to autostart. So, Unraid starts writing parity to that original parity (new data) disk, overwriting its data.

 

You should get a flash backup any time you change any settings you don't want to lose. And you absolutely must get a new flash backup if you make any changes to disk assignments.