First a bit of background: I had this running very smoothly on stoneburner, and inadvertently ran... you guessed it omv-update without reading the warnings about such things.
Needless to say I gleefully broke my install pretty horribly.
I decided it was a fine time to do a clean install, so I pulled down the iso and tried to install. This did not go smoothly either, which surprised me substantially; the installer kept throwing errors on the network configuration, though they weren't terribly clear.
After that I opted to try the debian bootstrap methodology but then suddenly discovered the issue that I most likely stumbled into on the erasmus install: the network firmware for my proliant built in network card is now classified as non-free (and thus not included in the base debian install).
To resolve this issue, simply pull down the firmware .deb file (https://packages.debian.org/je…ll/firmware-bnx2/download) and copy this to the 'firmware' folder on your usb thumbdrive prior to starting the installer (this could probably be done to the OMV3 image as well, and I will probably test this at some point)
Once that is done, I simply proceeded through the normal deb install, as highlighted in this post (though that is the OMV2 install): How to Install OpenMediaVault over Debian
However I found this easier at step 2, rather than using an editor as the file doesn't exist on a clean debian install (shout out to solo0815 here as I got this from his guide):
echo "deb http://packages.openmediavault.org/public erasmus main" > /etc/apt/sources.list.d/openmediavault.list
At step 3 I then followed his directions again, and brought in the gpg keys:
Now one would think that you could just go ahead and install openmediavault using apt-get (and you would be close); but it then screams about postfix not being installed and being dependent, so you do in fact need to knock that out first
Then voila fire off
So I am now up and running on the old monolithic piece of datacenter hardware I got handed down, and while it was probably quite a bit rougher than most OMV installs, I have been through much worse. With software I paid for.
Special nod out to both jodumont and solo0815 for their guides, as I basically hacked it together from those two.