Rebuild nothing..

[zeyoner]

Here's my situation..

 

Unraid 6.7.2

4x10TB - Data

2x512GB - Cache

Drives are encrypted

 

As of late I've been receiving errors on two (Disk 1 & 3) of the 4 hard drives. I've had to rebuild four times already. Disk1 is the only drive with data. I decided to remove the two drives in question and re-use disk2 as disk1. I did a new config preserving the cache. Powered down and removed disk1 & 3. Booted up checked the box stating the parity drive is good. Disk2 now being used as disk1 was then added to the array as disk1 which then needed to be formatted and rebuilt. I used the same passphase to unlock the drive. After 14 hours of rebuild all of my docker containers are gone and so is my data. I have one folder which I assume was moved from cache.

 

I still have the original disk1 untouched however I do not have a keyfile even though I know the passphase. Please tell me there's light at the end of this forsaken tunnel!

 

 

[JorgeB]

1 minute ago, zeyoner said:

then needed to be formatted

Format is never part of a rebuild, also if you removed disks from the array, parity wouldn't be valid anymore, even if those disks were empty.

[zeyoner]

Would the current keyfile still be valid for disk1? Would I be able to put back disk1 and recreate the parity?

Edited November 13, 2019 by zeyoner

[JorgeB]

Just now, zeyoner said:

Would the currently keyfile still be valid for disk1?

Should be.

 

Just now, zeyoner said:

Would I be able to put back disk1 and recreate the parity?

Yes, as long as disk1 is healthy.

[zeyoner]

3 minutes ago, johnnie.black said:

Format is never part of a rebuild, also if you removed disks from the array, parity wouldn't be valid anymore, even if those disks were empty.

I assumed it had to seeing that I was now in theory moving disk2 to disk1's slot.

[JorgeB]

Format deletes everything on the disk and updates parity accordingly.

 

[zeyoner]

9 minutes ago, johnnie.black said:

Should be.

 

Yes, as long as disk1 is healthy.

Disk1 has been kicking back an error although it rebuilds and functions for days then kicks an error causing me to have to rebuild. Man I can't wait to get home and rebuild that parity. So moving forward how should I go about doing this?

 

1. Stop array
2. Power off
3. Remove disk1 (disk2)
4. Insert disk1
5. Power on
6. Here's where I get a bit confused
7. New Config (Preserving Cache)
8. Add same parity
9. Add disk1
10. Start Array with correct passphase
11. Allowing Unraid to rebuild parity

Will it rebuild parity and leave disk1 as is?

 

Edited November 13, 2019 by zeyoner

[JorgeB]

1 minute ago, zeyoner said:

Will it rebuild parity and leave disk1 as is?

Yes, just make sure you don't assigned old disk1 to parity slot, and don't check parity is already valid, only the disk assigned to the parity slot will be overwritten.

 

Unraid will ask for a new passphrase but just enter old one.

 

 

[zeyoner]

2 minutes ago, johnnie.black said:

Yes, just make sure you don't assigned old disk1 to parity slot, and don't check parity is already valid, only the disk assigned to the parity slot will be overwritten.

 

Unraid will ask for a new passphrase but just enter old one.

 

 

Thank the data hoarding gods! I will execute this once I get home. Thanks a lot Jorge!

[JonathanM]

56 minutes ago, zeyoner said:

Thanks a lot Jorge!

ROTFL @johnnie.black

[JorgeB]

16 minutes ago, jonathanm said:

ROTFL @johnnie.black

Jorge is my actual name, so no worries , unlike @trurlwho keeps getting called constructor.

Edited November 13, 2019 by johnnie.black

[zeyoner]

I meant to ask. What did I do wrong? After the "New Config" when I re-added the parity drive and disk1 (disk2) and checked the box that states that the parity is good. Shouldn't it have rebuild disk1 (disk2)?

[itimpi]

Just now, zeyoner said:

I meant to ask. What did I do wrong? After the "New Config" when I re-added the parity drive and disk1 (disk2) and checked the box that states that the parity is good. Shouldn't it have rebuild disk1 (disk2)?

Parity is not good if you have made any change to the disk assignments.

[JorgeB]

You did many wrong things:

 

-new config is not used to rebuild a disk

-format is never part of a rebuild

-removing disks from the array invalidates parity, even if the those disks don't have data.

[zeyoner]

I see. 

 

[trurl]

In future, please ask on the forum before attempting to make any changes of any kind (add, remove, replace) in your disk assignments.

 

If you understand how parity works, and if you understand what format does, then you can figure these things out for yourself. But it seems most people don't even know what format does, much less how parity works.

 

[Dissones4U]

2 hours ago, trurl said:

much less how parity works

That's the big one, I've seen several threads in just the last few days with folks formatting an array disk and thinking they could rebuild it from parity, not understanding that erasing data from the array erases the data from parity as well....

[trurl]

I think that mistake is caused more by people not understanding the word "format", a word that everyone seems to think they understand, but really have no idea of what happens specifically. "Format" doesn't mean "get this disk ready to use (again)", whatever that might mean exactly.

 

Format means "write an empty filesystem to this disk". That is what it has always meant in every operating system you have ever used. Unraid treats that write operation just as it does any other, by updating parity. So after formatting a disk in the parity array, parity agrees the disk has an empty filesystem, and rebuilding a formatted disk from parity will result in an empty filesystem.

[zeyoner]

Thank you all. Yes I agree it appears I have misunderstood a lot. Lesson has been learnt!

Edited November 13, 2019 by zeyoner