Comment # 21 on bug 1223167 from James Carlson

I think I've got a good course of action now; thanks.

I mounted up the DVD while running 15.4, and saw this:

% cat
/run/media/carlsonj/openSUSE-Leap-15.5-DVD-x86_64491/repodata/df6fa38c088f2cbd6f718b30d09ce24654b85a0ca5152437ae8c8d9b60473b90-primary.xml.gz
> /dev/null
cat:
/run/media/carlsonj/openSUSE-Leap-15.5-DVD-x86_64491/repodata/df6fa38c088f2cbd6f718b30d09ce24654b85a0ca5152437ae8c8d9b60473b90-primary.xml.gz:
Input/output error

I think if I'd seen an "Input/output error" message somewhere from the
installer, I certainly would have known that something was going very wrong
earlier. It'd be nice if errors were reported, but (obviously) this is a really
obscure one and I can't fault the installer for missing it.

I will:

- reconfigure the /var partition using ZFS canmount=off and submounts for the
things I really care about (such as /var/mail)
- update everything, re-download, and retry via a USB device
- if I can't get that to work, then fall back on live upgrade via zypper

Thanks! I think I'm set.