Array missing disk configuration.

[fatalfurry]

I had multiple power outages today due to bad weather. this caused my unraid server to do an unclean shutdown. After booting it back up my array devices are unassigned. What should be my first steps on restoring my array? (Diagnostics attached)

 

 

tidehunter-diagnostics-20190720-1652.zip

[Harro]

If you have a current back up of your flash drive. I would copy that over to your usb drive and start your server again. 

Otherwise, and I am not as qualified on this as others, if you know which drives are your parity drives, assign them to those slots and the other drives can be populated in whatever order in the array. A parity check will start after a restart.  

[JonathanM]

3 hours ago, fatalfurry said:

multiple power outages today due to bad weather. this caused my unraid server to do an unclean shutdown.

Not good, as you found out.

3 hours ago, fatalfurry said:

What should be my first steps

Purchasing a battery backup and configure it so the server shuts down cleanly.

 

Do you have status emails sent to you periodically? Do you have diagnostics from before this event? Screenshot of array? Anything?

 

The picture you posted seems to show 2 parity drives, problem is with parity2, disk order matters if you need to keep parity valid with reassignments.

[fatalfurry]

I am purchasing a UPS this week. This was always something on my list, but never got around to.

 

I found an old diagnostics that has all of my drives listed in the vars.txt file.

 

tidehunter-diagnostics-20181206-1608.zip

 

I can map out all of the disks in their correct positions, but how do I set them up to not format and clear the data? 

[Harro]

If you can set your parity or parity drives in the correct slots, meaning the correct parity drive for slot 1 and or correct for slot 2, it should not matter which slots the other drives are in. Reboot and make sure box for write parity corrections is not checked. Parity will rebuild at that point.

 

Good idea about a UPS. I have 2 running, one each on my servers. Has saved me a few times. 

[JonathanM]

1 hour ago, Harro said:

it should not matter which slots the other drives are in.

Yes it does. Parity1 doesn't care about drive order, but Parity2 relies on the disk assignments staying the same. If you correctly assign all the drives, you can check the option indicating parity is already valid, and just complete the parity check. If the drives are not in the same order, Parity2 must be rebuilt.

 

3 hours ago, fatalfurry said:

how do I set them up to not format and clear the data? 

Set a new config, and assign all the drives correctly. Does the historical diagnostics you recovered have exactly the same complete list of drives?

[itimpi]

If you are going to rebuild parity anyway, then the safest thing to do is:

• Use New Config to reset array
• Assign all the data drives as you think they should be.   At this stage do not assign the parity disks.
• Start the array.    UnRaid will recognise any drives that have previously been array drives and will leave their data intact.  If you have managed to get the correct assignments for the data drives all the drives should have mounted and their data now be visible.   If not then now is the time to stop and ask for advice.
• stop the array and assign the parity drives
• start the array and let the parity drives be built based on the currently assigned data drives.

The key point is to make sure that you do not assign a drive as a parity drive that should be a data drive as doing so loses its contents as soon as you start the array and Unraid starts to build parity.

[Harro]

7 hours ago, jonathanm said:

Yes it does. Parity1 doesn't care about drive order, but Parity2 relies on the disk assignments staying the same. If you correctly assign all the drives, you can check the option indicating parity is already valid, and just complete the parity check. If the drives are not in the same order, Parity2 must be rebuilt.

Just for my understanding and thanks jonathanm for correcting me. If he only had 1 parity drive, the order of the data drives do not matter but with the second parity drive, he needs all the correct data drives in the correct slot assignments. If I am understanding this and if a person wouldn't know where any data drives were assigned and didn't know exactly which parity drive went, but knew which drive/s were used for parity, would it be safe to assign 1 of those drives as parity and let the server rebuild and the add the second parity and rebuild again? After second parity is added a new text file is added in flash drive under config folder called "DISK_ASSIGNMENTS.txt". Now if I understand instead of backing up my whole flash drive I could just print this txt file out along with a screen shot of my web gui main page to get all the correct assignments of drives going forward. Rinse and repeat after drives are upgraded so I would have a current list of all drives and assignments.

 

Reason asking is I am in the process of adding 6 new drives and plan on rebuilding 2 at a time and want a fast way to record my drives, just in case.

[JonathanM]

The critical piece to get your head around is whether or not parity is still valid. If all your drives are perfectly healthy, rebuilding parity is no big deal, it's just time consuming. If, on the other hand, you have a drive failure, or two, then reassigning the remaining drives to the correct slots is the only way to emulate the failed drives so you can rebuild them.

 

It gets complicated, you have to use the command line before starting the array and after setting the correct assignments, but it's doable.

 

For safety's sake, it's always best to keep a current list of which serial number drives are assigned where. Taking a fresh flash backup each time something major is changed is wise.

 

In your scenario where you are making good guesses as to which drive goes where, if you needed to rebuild a single failed drive, then yes, you would only assign parity1. However, if you were truly guessing, you would only have a 50% chance of getting it right, and may end up having to repeat the trust parity rebuild a second time with the correct parity drive, as putting parity2 in parity1's slot would result in invalid parity and a failed rebuild.

 

Again, if you don't care if parity is invalid when you assign the drives, the only thing that matters is that you properly ID the parity drives in either order, and you can build parity from the healthy data drives. It's only in a failed drive scenario where you need to recover that it's important. You can build either or both parity drives at any time as long as your data drives stay healthy.

 

The OP's recovery scenario was risky, power failures can kill drives as well as corrupt data. I was trying to detail a recovery path with the highest possible chance of success.

[fatalfurry]

Thank you everyone for your input. I've taken jonathanm's advice on assigning all of my disks as they were previously including the correct drives for parity 1 and parity 2. At first glance everything is looking good and I'm running a parity check.

 

Looking into UPSs I've realized I don't know enough about the nuances. Are there any recommendations on a UPS that can be rack mounted?