JonathanM

Did you apply the new config and select the disks again in the main GUI?

This.
It's the number of drives physically connected when you hit the start button.
You could always connect the drive after you start the array if you want to use it as an Unassigned Device, and make sure it's unplugged if you need to restart.

Assuming you assigned the drives accurately, yes. You still need to do a parity check to be sure things are synced up, but there should be few if any errors.
 
If you are at all unsure about which drive is parity, don't proceed until you are absolutely positive, as the drive assigned to the parity slot will be overwritten. Drives in the data slots will be left as is.

Yes.
Yes.

Short answer, no.
 
Long answer, you can allocate space (vdisk) on an array drive or pool that can be seen as a physical drive to the VM, but the content won't be accessible through Unraid. 

If for some reason the USB Flash Creator tool cannot be used, or your USB flash device is not detected, it is possible to manually format and prepare a bootable USB flash device. Note: this method only works for devices 32GB and smaller.
Plug the USB flash device into your Mac or PC.
Format the device using the FAT32 file system. It must not be ex-FAT or NTFS.
Set the ‘volume label’ to UNRAID (case-sensitive, use all caps).
Go to the downloads page. to get the zip file for the release you want to use.
Choose a version and download it to a temporary location on your computer (e.g. a “downloads” folder).
Extract the contents of the newly downloaded ZIP file onto your USB flash device.
Browse to the USB flash device to see the newly extracted contents from your Mac or PC.
If you need to enable UEFI boot, rename the EFI- directory to EFI
Run the make bootable script appropriate to the OS you are using:Windows XP
double-click the make_bootable file.
Windows 7 or later
right-click the make_bootable file and select Run as Administrator.
Mac
double-click the file make_bootable_mac file and enter your admin password when prompted.
Linux:
copy make_bootable_linux file to hard drive
unmount (not eject) USB drive
run the following command from wherever you unpacked it to on your Linux system:
sudo bash ./make_bootable_linux
NOTE: during the process of running this script, the flash device may seem to disappear and reappear on your workstation a few times – this is expected behavior.

Preclear is NEVER required. It's purely a means to thoroughly test a drive, and optionally speed up the process if you are adding the drive to a NEW (not replacement) data slot in an already valid parity array. Unraid will automatically clear (not preclear) a drive assigned to an additional data slot, but if a valid preclear signature is found on the drive, Unraid will skip the clearing phase and immediately offer to format the new drive slot, saving several hours.
 
Rebuilding a drive always writes the emulated image to the entire capacity of the drive, regardless of the content of the drive, cleared or otherwise.
 
Reallocated sectors are not necessarily fatal, but depending on how many and if they are increasing it may be a sign of impending failure. A small number that doesn't increase over time is probably fine.

No.
 
There is no "installation" as Unraid runs in RAM, so it's loaded from the license USB stick into RAM on every boot.
 
Here is the forum section on running Unraid as a VM. While not officially supported by Limetech, it has been done successfully on several hypervisors. Since Unraid boots from a USB, runs in RAM, and itself hosts VM's, running it as a VM can be rather complicated.
 
https://forums.unraid.net/forum/46-virtualizing-unraid/

Skip the preclear, just replace the drive, build parity, do a parity check, do a long smart test on the drive.
 
Preclear is not productive for your situation, you want to get valid parity back in place ASAP. If you had a new drive in anticipation of replacing a drive that was still functioning, then preclear might be of some value, but only as a stress test to weed out infant mortality. You will get that same level of testing by rebuilding the drive and checking parity, and the bonus is you will be protected that much sooner. If the new drive fails during the process, you aren't in any worse shape, just back to needing another drive.
 
If you were getting a new drive to ADD to a NEW data slot, not replacing a drive, then preclear could save some time as well as give you a confidence check in the drive before trusting it in the array. This does not apply to your situation.

What is your split level?

Have you masked off or disabled the 3.3V reset pins on the drives?

Try this
plink.exe -batch -ssh -pw passwordhere useridhere@serveriphere powerdown  

powerdown

All offline licensing will need to be handled by emailing Limetech.

If the container is referencing or writing to any files that have already been moved to the array, the array will stay spun up. Cache: yes means NEW files written to the share will be on the cache, then when mover runs they will be transferred to the array if they aren't being held open by something.
 
Cache: prefer will attempt to move the entire contents of the share to the cache drive, assuming there is enough free space. Once again, any files that are open will fail to move.

Each parity must be as large or larger than any data drive.

Try completely redoing the flash drive, the same way you set it up to begin with, and copy the license key file into the config folder.

Each data disk can only have one volume, but different disks can be different formats.
 
With 3 HDD's, you could have
1 Parity
1 XFS
1 XFS-encrypted

You need to correct the LAN Network.

That second license thing was from an era when having a USB key die meant you could be down several days waiting on a replacement license file from Limetech. It was meant to allow you to keep a ready backup so you could be up and running instantly vs. waiting.
 
Now that key replacement is online and automated, having a second license unused on standby is no longer really needed.
 
The discounted license was never really MEANT to run a second server, but of course you could.
 
Now, I'm not a Limetech employee, and they surprised EVERYONE with a black friday / cyber monday license sale last year, so anything is possible in the future, but for right now, it's just posted prices.

Unclear if you understand this, so I'll just say it. You can't have 18TB data drives with a 12TB parity.
 
So, I'll outline what is possible with the drives you listed.
1. Replace parity with one of the new 18TB, rebuild parity and do a subsequent parity check.
2. Rebuild one of the 6TB drives with the old 12TB parity drive, do a non-correcting parity check.
3. Rebuild the other 6TB drive with the other new 18TB drive, do a non-correcting parity check.
 
What I've outlined keeps the array data shares and applications available the entire time, albeit at reduced performance which is unavoidable.
 
If at any point there are errors, those need to be resolved before moving on to the next step.

It would probably be faster to attach the drive to the windows machine and copy to it across the network.

No. The only restriction is no data drive can be larger than either parity drive.
 
Having a 12TB and a 10TB parity at the same time is not a problem, you are just limited to 10TB data drives until you upgrade the second parity.