itimpi

Parity contains none of your data so it being disabled does not affect your data unless a data drive fails in the meantime..   It should all still be there after a reboot although the parity drive will remain disabled until action is taken to correct it.
 
I can see that you started getting what looks like a cabling/power issue on the parity disk shortly after mid-day on 12th and shortly after that started getting write errors on the parity which is what will ha e caused it to be disabled. drive.   Shortly after that you started getting read errors on other drives that also look like cabling/power issues and eventually these stated getting read errors.   The SMART information for the  drives does not show drive faults so no indication the drives themselves have failed.
 
Since most drives appeared to be affected in the end I would be looking at what they share.   You want to check that your HBA is well seated and that there are no power issues.  While you are at it check both the SATA and power cabling.

It is normal for top level folders on drives to become shares with default settings unless it is a pool for which user shares have been disabled in the pool settings.
 

Sounds as if somehow the docket.img file did not get backed up and a new one got created.
 
You will need to reinstall your docker container binaries (with previous settings intact) via Apps->Previous Apps.

If you have a recent backup of the config folder then you should be able to copy it to a fresh flash drive to keep all your current settings.   You will have to go through the licence transfer process to get the array back online but that should be easy enough.

You can use the New Config tool and assign disks 1-3 plus the new parity you want to use.  To avoid mistakes I would recommend using the option to keep current assignments and then return to the main tab to make corrections as needed.  Then when you start the array the contents of disks 1-3 will be left intact and parity will be rebuilt based on the contents of disks 1-3.

In principle Unraid is hardware agnostic and recognises disks by their serial number and not by how they are connected so the transition is painless. , although it can get a bit more complicated if one of the systems used a RAID controller for the disks.
 
I was not sure if you  know what disks belong where, and if not you may find this section of the online documentation helps with sorting out the drives. 

A disk needs to be rebuilt to clear the disabled status.   The rebuild process makes a physical drive match the emulated one so check that the contents of the emulated drive are what you expect.   The diagnostics suggest the emulated drive is mounting OK.
 
if you think the physical drive is OK then you can follow the procedure to Rebuild a drive onto itself as documented in the online documentation accessible via the ‘Manual’ link at the bottom of the GUI or the DOCS link at the top of each forum page. The Unraid OS->Manual section in particular covers most features of the current Unraid release.

The settings you have mean it is only listening for other servers.   As mentioned in the syslog server link to get your server to record its own entries you need to set either the Mirror to Flash option OR the Remote Syslog server field to the address of your Unraid server.

You can disable a plugin by renaming its .plg file in the config/plugins folder on the flash drive to have a different file extension and reboot.   Reverse the process to re-enable.

Going through the User Share sub-system is known to have a non-trivial impact when performance matters.
 
if the ‘appdata’ share is all on the cache, then you can remove the secondary storage setting, and then make sure Exclusive shares are activated under Global Share settings.   With this combination going via /mnt/user/appdata will have the same performance as going via /mnt/cache/appdata.

If you are not sure of the state of the server you could try running another non-correcting check.   If there are no issues it should report the same number of errors (but you could skip this check if you think the server is stable) and you can then run a correcting check to fix them.   Note that a correcting check reports as ‘errors’ every one it corrects so you should get the same count again.   Future checks should then report 0.

You should have the current terminology in the online documentation accessible via the ‘Manual’ link at the bottom of the GUI or the DOCS link at the top of each forum page. The Unraid OS->Manual section in particular covers most features of the current Unraid release.
 
You are likely to get better informed feedback if you attach your system’s diagnostics zip file to your next post in this thread. It is always a good idea when asking questions to supply your diagnostics so we can see details of your system, how you have things configured, and the current syslog.

You will always have some space used once a drive has been formatted to hold the directory structures.    It can is normally something like 1 to 2 % of the total disk size depending on the file system being used.

You can go directly to the current release.   

Your existing licence is entitled to Lifetime upgrades since you bought before the new licensing scheme came into affect.   If you want you can upgrade it to Pro but that is not necessary unless you want the support for additional drives.

As was mentioned - leave the parity disk as it is because then it will emulate the missing disk1.    Doing anything else is far more complicated and ,making an error would lead to data loss.
 
Assuming you have left the parity disk in place, then just plug the replacement disk in as disk1.  When you then start the array Unraid will rebuild the contents of the 'emulated' disk1 onto the replacement physical disk1 so it matches the emulated one.   When that completes your array will be back in a protected state.

You need to run without -n (the no modify flag) or nothing will be done.   If it asks for it add -L.

Not quite as you do not seem to have any of the Library share on the ‘cache’ pool.    
 
You either correct the settings for the Library share to say that its primary is the ‘plex’ pool leaving the files where they are, or alternatively leave the settings as they are and move the Library folder (and its contents) from the ‘Plex’ pool to the array to match the settings.

@jdhill777 You should remove the Mover Tuning plugin and then run mover manually.

Have you tried using the Manual Install method rather than trying to do it via the GUI?

You cannot transfer a trial licence to a new flash drive.  

You need to rerun without -n and adding -L.

You could try installing the File Sctivity plugin.
 
we might also be able to suggest something if you post your system’s diagnostics.

Try removing the Mover Tuning plugin  and then try again.
 

Using the Linux ‘mv’ command should work fine as long as you make no mistakes in the command.
 
A better solution might be to use the Dynamix File Manager plugin as it will provide a GUI interface and also protect you against certain types of actions that might result in data loss.