wobbler's questions

I have a 20TB (4x5TB) RAID5 aray (please hold comments about RAID5, I know a lot of people don't like it) that I recently setup, through Webmin, on 18.04.3LTS ubuntu server.

I am not creating the filesystem (through Webmin) and it seems to be taking a very long time - it's been going (I think) for at least 24 hours now.

The command Webmin runs is

Executing command partprobe ; mkfs -t ext4 -c -q /dev/md0 ..

Since running, I am just getting the equivalent of the pinwheel - there is no progress bar to indicate if it's still actually working or has stalled.

In the 'Running Process' section of Webmin, the following two are at the top of the list

27638   root    12.7 %  [md0_raid5]
21798   root    10.4 %  badblocks -b 4096 -X /dev/md0 3662728703

I suspect maybe I ticked an option for it to check the array for badblocks, while creating filesystem, which might slow it down considerably? but I don't know what I don't know here. Additionally, the activity LED on the drives are showing constant activity.

I am guessing this all means it's still progressing, but I was hoping there may be a command to run that may give me a progress indication? or may someone has completed a similar process and can give me an indication of how long I should wait before quitting and staring over?

UPDATE: this thread suggest it's badblocks and I'll probably be waiting 400+ hours...

If so, is there a way to kill the badblock process and have it just finish off the mkfs.ext4? Else, what commands should I run to start it again with just filesytem creation?

I Recently noticed an lightweight app (Sonarr) wasn't running, so when into webmin to find a fidk fill error. '/' was 100% full. I have hunted around and sound a few commands to get a bit of short term space back (down to 96%), but there shouldn't be that much usage. I'm just running Ubuntu Server LTS18 and a couple of apps on a 120GB SSD. But I am seeing the below and cannot (and do no know how to) find where the heavy directories and/or file are in /.

Filesystem                                 Size  Used Avail Use% Mounted on
udev                                       7.3G     0  7.3G   0% /dev
tmpfs                                      1.5G  2.8M  1.5G   1% /run
/dev/sde2                                  110G  104G  4.6G  96% /
tmpfs                                      7.3G   12K  7.3G   1% /dev/shm
tmpfs                                      5.0M     0  5.0M   0% /run/lock
tmpfs                                      7.3G     0  7.3G   0% /sys/fs/cgroup
/dev/loop0                                  90M   90M     0 100% /snap/core/7917
/dev/loop1                                  90M   90M     0 100% /snap/core/8039

TL;DR - How do I convert my imported Z-pool to a RAID setup (or LMV?) that I'll be able to recover/rebuild when/if a disk fails?

I migrated from FreeNAS. Had a RAID-Z (equivelant to Raid 5, I think - where one disk can fail) made up of 4 disks.

I moved, recently, to Ubuntu Server and was able to import the Zpool without too much fuss. It's working - I have access etc.

I installed WEbmin for ease, and noticed that the volume isn't showing in the raid section. I can see the individual disks on the partitons sections, but nowhere else.

So it occurs to me. What if a disk fails now. What happens? how will I rebuild it without the GUI. Can I even rebuild it. Is there a way in Webmin to covert the zpool to something it will be able to work with should a disk fail?

Side note - the dashboard of webmin is report a pretty huge total storage amount (i only have about 20TB plugged in... 4x5TB zpool disks and a small SSD for OS.)

Local disk space    8.95 TB used / 96.63 TB free / 105.57 TB total