Oh, I see. Not use the old disks at all.
If I do that, would I need to let this parity rebuild finish, or stop it, do the New Config, build the new array, and let it basically start over with just the new drives?

But if it was already working well, maybe just keep things as they were except for a new larger parity (and maybe parity2), and then you can add those other disks one at a time as needed for capacity, and let Unraid clear them.

No point in building parity then doing New Config and building parity again.

Do you want dual parity?

Just now, trurl said:

But if it was already working well, maybe just keep things as they were except for a new larger parity (and maybe parity2), and then you can add those other disks one at a time as needed for capacity, and let Unraid clear them.

That's sort of where I'm headed now, unless you say something that changes my mind in the next few minutes. :)
It says it'll take about 9hrs to rebuild the parity, and it's finding errors, which I call BS on, because my parity has been perfect for years. There's no reason for it to go sketchy now.

Just now, trurl said:

Do you want dual parity?

I assumed it was better protection. Is it not? It lets up to 2 drives fail without data loss, right?

1 minute ago, trurl said:

No point in building parity then doing New Config and building parity again.

That's sort of why I was asking if you thought I should stop the rebuild.

If you want dual parity, you can build both at the same time.

Also, no good reason at all to call BS on whatever errors you are seeing. Not even clear exactly what kind of errors they are. You can't be having parity sync errors while building parity, since parity basically doesn't exist yet. So you are probably having I/O errors due to connection problems or something.

Attach Diagnostics ZIP to your NEXT post in this thread.

Then after checking those to see what the errors are, we can consider stopping it, fixing them, and then trying again with dual parity.

tower-diagnostics-20260102-2046.zip

Here you go, have a gander and see what looks hokey to you...
Oh, and thanks for your time with this!

Looks like parity2 is bad. I assume you wanted to replace it with a larger one anyway.

Just now, trurl said:

Looks like parity2 is bad. I assume you wanted to replace it with a larger one anyway.

It wasn't bad until I started this move about an hour ago. I run parity checks once a month, and have never had a single error.
And no, I was replacing parity1, since it forced me to make that the largest one.

Parity2 is logging actual disk errors.

Jan  2 20:26:07 Tower kernel: critical medium error, dev sde, sector 148701472 op 0x0:(READ) flags 0x0 phys_seg 63 prio class 0
Jan  2 20:26:07 Tower kernel: md: disk29 read error, sector=148701408

I know you were replacing parity instead of parity2, but it is existing parity2 that is giving the errors. You should be able to see that in the ERRORS column on the MAIN page.

You can replace both parity disks at the same time and so rebuild both parity disks at the same time.

Well that sucks. I wonder if it was a little bit marginal, and moving it between chassis was enough to kill it?

So that being the case, am I better off stopping the rebuild, and going the New Config route?

Don't you want to replace both parity disks with larger disks? You can't add any data disks larger than either parity.

3 minutes ago, trurl said:

You can replace both parity disks at the same time and so rebuild both parity disks at the same time.

Just now, trurl said:

You can't add any data disks larger than either parity.

Wait...EITHER parity? That's not clear from the docs. I thought that just one of the parity disks had to be at least as large as the largest data disk.
Well...crap. I guess I'll have to use 2x of the 6TB drives. That will reduce the array size, but that was the original plan anyway, so it'll be okay.
Maybe one day I'll be able to afford to replace them with something larger.

1 hour ago, trurl said:

Each parity disk must be at least as large as the largest single data disk, but parity disks don't have to be the same size.

https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array/overview/#driving-principles

1. Use your largest drives for parity - Data disks can't be larger than your parity disks, so use your biggest drives for parity to avoid future expansion limits. If you use dual parity, both drives should be at least the size of your largest data disk, but they can be different sizes from each other. No disk can be larger than your smallest parity drive.

So after you reserve 2 of the 6TB disks for parity, what is on the remaining unassigned disks? Do they contain all of your array data?

That would have been useful info for me to have processed earlier. Note that I said processed, and not necessarily seen. lol

Just now, trurl said:

So after you reserve 2 of the 6TB disks for parity, what is on the remaining unassigned disks? Do they contain all of your array data?

They do, but you want to hear something really stupid?
I didn't have a way of labeling the drives, and wasn't expecting to move them, so now I don't know which ones are parity and which ones are data. 🤦‍♂️
I'll basically have to treat them as blank drives, and copy everything over again, once the array is rebuilt. At least it'll be internally, rather than over the network, which hopefully will be quicker.

Probably simpler to just go with your existing array data disks and both larger parity disks, and forget about the contents of the other new disks.

And you don't need to copy anything. After you get parity built, if you want to replace one of the smaller data disk with a larger disk, just replace it and rebuild.

1 minute ago, trurl said:

Probably simpler to just go with your existing array data disks and both larger parity disks, and forget about the contents of the other new disks.

Yeah, I think so.
In that case, would you just add the new drives to the array, or use the New Config?

Just now, trurl said:

And you don't need to copy anything. After you get parity built, if you want to replace one of the smaller data disk with a larger disk, just replace it and rebuild.

But there are more small disks than large ones. How would that work?

In any case, do I need to stop this parity rebuild and replace the other parity disk, so it can build once?
Also, can I add the new array disks at the same time?

2 minutes ago, Elmojo said:

But there are more small disks than large ones. How would that work?

You don't have to replace all the small disks now. You have to replace and rebuild one at a time anyway.

1 minute ago, Elmojo said:

In any case, do I need to stop this parity rebuild and replace the other parity disk, so it can build once?

Yes

1 minute ago, Elmojo said:

Also, can I add the new array disks at the same time?

You could add them to new slots and Unraid would clear them. But would you rather use some of them to replace some of the smaller disks?

Ok...the parity rebuild is stopped.
So I'm getting confused again.
At this point, my best option is to replace both parity drives with 2 of the new 6TB disks, correct?
Do I need to let that fully rebuild a new parity set before I move on to adding any of the 6TB drives to the array, or can I do that now?
I don't know what you mean by adding them to new slots, or how that's different than adding them to the array, or how either of those processes differ from replacing a 4TB disk with a 6TB disk.

It's all becoming a blurr...

Does this help?

The suspense is killing me... lol

You need to let (both) parity rebuild first. Technically, you could add other disks to new slots at the same time, but let's not complicate things.

Replacing a disk means assigning a new disk to a slot that already had an assigned disk. Replacing 4TB disk1 with a 6TB disk by assigning the new 6TB disk as disk1, for example. The contents of that original disk would be emulated by reading parity plus all other disks and getting the data from the parity calculation. Those emulated contents would be rebuilt (written) onto the new disk. This is really the whole point of parity, allowing you to replace a disk (possibly failed beyond the point of copying it) without losing its contents.

And, technically, with dual parity, you could replace 2 disks and rebuild both at once, but safer to do one at a time.

Adding a disk (to a new slot) means assigning a disk to a slot that didn't already have an assigned disk. such as disk7. When you add a disk to a new slot in an array that already has valid parity, Unraid must clear the disk (fill it with zeros) so parity remains valid. All those zeros don't affect parity.