Now that CentOS8 has been released, I gave SME 10a4 a try out. Installing with single disk worked fine, I was able to create users, run webmail, create ibays. I didn't try to join a PC to it, as I don't have a spare one to use. I also couldn't map a drive to it from my W10 workstation, but I swear I had done it before, but maybe not.
I was also able to use 2 disks and create a raid1 system. Swapping the disks, the system booted fine. If I removed the second disk, the system would boot fine. If I added files, then booted with both disks in, the second disk would rebuild and be added back to the raid1. If I removed the first disk, then it wouldn't boot all the way. It would enter emergency mode. From what I found, it seemed like it was stopped on some dracut emergency screen. Trying things from various sites didn't fix the issue for me with booting off the second drive only.I think it was something to do with not knowing the UUID of the second drive, but I won't swear to that.
I was also able to take 3 disks and create a raid5. /boot was raid1 on the three disks, / and swap were raid 5 using LVM. If I remove the 1st disk, and put the old 2nd and 3rd disks, 1st and second, then my server boots to the emergency screen with the same UUID missing errors. Same if I put them back in the original order and remove the 2nd or 3rd disk.
The raid devices were always /md126 and md127. I found a way to renamed them to /md0 and /md1, but then I wasn't able to reboot after changing them. There was another dracut command I found on some site, but running those commands didn't fix anything for me, so quit trying to rename them.
Another thing I ran into was an error that I had multiple volumes with the same name. To fix that, I used the instructions to go to the shell, and use vgrename <UUID of drive> <any_name>. That would let me proceed. You can also do a new install on the single disk and change the volume name there. After the install, you can then use it with other drives.
There were my experiences, and nothing real scientific to what I tried, but hopefully this, and other info provided, will help someone get us further to being able to release SME10. I don't support SME, I just run it at my home. I do what I can with the horde webmail product, and all of the changes I have made in 9.2, all seem to work in SME10. I did add 2 patches for horde in the bug system, so bring things on par with what I have done for 9.2 as well.
Thank you,
John