numbers are UUID of disk, select filesystem to see what is the selected devices.
I appreciate you taking the time to read and reply to my post!
Since my OMV is an older version [5.6.26-1 (Usul)], my Filesystems screen does not show the UUID there. 
But now that I know what that string of characters is called (thank you!), I was able to identify the drive from my Diagnostics > System Information > Report window.
The bad drive is sdg, serial number ZVT6FS12.
Thank you, so much!!!
I am a total noob at Linux, OMV, Portainer and Plex, even though I have had my server up and running for a few years. I have merely followed online tutorials and watched YouTube videos to get things set up. So, I know just enough to do what I have to do (follow the instructions), and try to not do anything that might cause a catastrophe.
I know I need to update my OMV, but before I tackle that (probably with a clean install, since I am so far behind) I have another issue: I currently have a DEGRADED zfs pool on my OMV install.
Pool status (zpool status):
pool: ZFStwo
state: DEGRADED
status: One or more devices are faulted in response to persistent errors.
Sufficient replicas exist for the pool to continue functioning in a
degraded state.
action: Replace the faulted device, or use 'zpool clear' to mark the device
repaired.
scan: resilvered 7.30G in 00:24:20 with 0 errors on Sat Jul 20 22:56:01 2024
config:
NAME STATE READ WRITE CKSUM
ZFStwo DEGRADED 0 0 0
raidz1-0 DEGRADED 0 0 0
53a02588-9ce0-3447-9fed-64ec59a3b064 FAULTED 0 3 0 too many errors
01d0d7be-8f0b-0d4f-95bb-b547b28b3296 ONLINE 0 0 0
e424e1ee-81cc-4848-a3a9-7608acc42ff7 ONLINE 0 0 0
errors: No known data errorsAs you can see, the faulted drive is identified with just a bunch of alphanumeric characters. But I cannot find any portion of that string in my list of Disks or in the S.M.A.R.T. data to identify the faulty disk.
I have spent hours searching and scouring the Internet trying to find some command I can use to help me identify the drives based on any portion of that alphanumeric string... but I am getting nowhere.
How can I identify the faulty drive so I know which one to replace?
The S.M.A.R.T. data. from each of these three drives is attached. I could not include them in a Code block because it would make this message too long to post.
Thank you so much for helping out!
dev-sdf drive Serial # ZVT6FS89 Extended Information.txt