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Have you actually formatted any of your disks in Unraid yet? Doesn't look like you have any filesystems to create anything on.

Correct. You must let New Config rebuild parity (don't check the parity valid box).

https://docs.unraid.net/unraid-os/manual/storage-management/#rebuilding-a-drive-onto-itself

You have one rebuilding and one missing disk, which is all 2 parity can do, so nothing is protected if another disk fails.
 
Doesn't matter if a disk is empty or not, an empty disk is not a clear disk. It still contains the metadata for the empty filesystem on the disk.
 
Even if disk6 happened to be a clear disk, Unraid won't remember whether or not all of its bits are zero so considers it to have bits that are part of current parity.
 
So you currently have no redundancy in your array.

A container you have already installed from the Add Container page stores its template on your flash drive in config/plugins/dockerMan/templates-user. They are XML you can examine.

Just put the registered .key file back in the config folder on flash.
 
If you don't have a copy of the .key file contact support.

Mover Tuning Plugin

The config folder from your flash has all of your configuration. I would edit disk.cfg to set the array to NOT autostart so you can confirm your drive assignments.

Problems communicating with multiple disks. Power would be a suspect. Are there power splitters involved?

Change Docker from macvlan to ipvlan.
 
Check filesystem on disk1.
 
Rush named pools 👍
 

USB not recommended for array or pools for many reasons.
 
Attach diagnostics to your NEXT post in this thread.

Nothing indicates the drives need to be replaced. You just have a corrupt filesystem on the pool.
 
If you're going to reformat cache to fix the corrupt filesystem, you need to get everything off it you want to keep.
 
In your diagnostics, logs/syslog.txt, starting with these entries:
Dec 16 21:17:00 Tower kernel: BTRFS critical (device sdb1): unable to find logical 9836280312331550720 length 4096 ### [PREVIOUS LINE REPEATED 47 TIMES] ### Dec 16 21:17:00 Tower kernel: BTRFS critical (device sdb1): unable to find logical 9836280312331550720 length 16384 Dec 16 21:17:00 Tower kernel: BTRFS critical (device sdb1): unable to find logical 9836280312331550720 length 4096 Dec 16 21:17:00 Tower kernel: BTRFS critical (device sdb1): unable to find logical 9836280312331550720 length 16384 Also, just after those entries (and also somewhat before) you have dumps related to macvlan. These have been known to cause crashes. The solution is to change Docker from macvlan to ipvlan. But we can deal with that later since you should
 

rootfs is where the OS files are (in RAM as mentioned). If you fill that up, the OS can't work with its own files, so all sorts of things can quit working.
 
You need to figure out what is writing to RAM.
 
Often a misconfigured host path for a container will be the cause.

Your appdata, domains, and system shares have some or all files on disk1.
 
Ideally, these shares have all files on cache or other fast pool with nothing from them on the array. If these are on the array, Docker/VM performance will be impacted by slower array, and array disks can't spin down since these files are always open.
 
Set these shares to Primary storage: cache; Secondary storage: array; Mover action: array --> cache.
 
Nothing can move open files so you have to disable Docker and VM Manager in Settings then run Mover.
 
You can see how much of each disk or pool is used by each user share by clicking Compute... for the share or Compute All button on the User Shares page.

Looks like your cache drive has disconnected. Possibly related, your system share has some files on disk2.

You can consolidate free space to one drive using some of the features of the unBALANCE plugin, or move things yourself using the Dynamix File Manager plugin.
 
It is possible to create multi-disk pools outside the parity array using btrfs:
https://docs.unraid.net/unraid-os/manual/storage-management/#why-use-a-pool
 
If you want to combine the capacity of multiple disks of different size, you would use the Single profile:
https://docs.unraid.net/unraid-os/manual/storage-management/#change-pool-raid-levels
 
Pools can also be ZFS but I have no experience with that.

That looks fine, says 65% used, are you still getting that 75% warning? As long as it's not growing it's OK. You might increase allocation to 30G if you want to keep the warning away. Then if you get it again we can take another look.

Are you sure you don't have the array started in Maintenance mode?

Note that none of the ways you worked on this problem earlier would fix unmountable.
 
Be sure to post the output of check filesystem so we can advise further.

Note that replacing the disk won't fix unmountable filesystem.
 
Since this is the last drive in the array, was it recently added? Did you let Unraid format the disk after you added it to the array? Do you think the drive had any data on it?

Did you let Unraid format your disks yet? Doesn't look like you have any filesystems for docker to live on.

You can always replace parity with a larger disk when needed and reuse old parity for Data.
 
Have you tested your old drives? Each disk in the array must be reliably read to reliably rebuild a disk. Parity by itself can recover nothing. 

Does your server have more than one ethernet port? I'm thinking you are seeing the IPMI port instead of the port Unraid would be on.

There must not be any RAID controllers involved in either system.
 
Assuming you only use the diskUnraid disks for array drives in dockerUnraid, and don't keep any existing dockerUnraid array drives, then New Config as linked above should work and your parity will still be valid if all array drives are assigned exactly as they were in diskUnraid. So you can check the parity valid box before starting the array and it won't rebuild parity. A parity check after would be a good idea just to confirm.

That doesn't show your cache anywhere near full. And appdata and system shares are on cache where they belong, and no other shares are currently using any of cache. So there is nothing for mover to do.
 
What are you looking at the makes you think your cache is filling up?