Comment # 14 on bug 1222429 from Lukas Ocilka

(In reply to Jiri Slaby from comment #10)
> AIUI, there is a cluster, someone has mounted a FS on it. There there is
> this installer (yast) which wants to probe all filesystems on the cluster,
> but not actually touch/write them, because they are mounted elsewhere.

Partially correct: YaST (Installer) needs to mount all filesystems to see what
is in them to provide options for upgrade (e.g., all compatible products to
upgrade "from"). But these filesystems are NOT mounted anywhere else. The point
of r-o mounting is to keep the FS "as is" (also/or ideally with noatime as that
may also change something).

And THEN, when a system to upgrade from is chosen, then this one and all
related filesystems are mounted r-w as the upgrade process is free to change
them (in fact "intended" to change them).