Comment # 4 on bug 982329 from Manfred Hollstein

By strace'ing lvs I found out that it spends a lot of time on trying to scan
255 /dev/loop devices... Hmm, yes, I had created a /etc/modprobe.d/50-loop.conf
file containing

  options loop max_loop=255

which is probably overkill, but the default 8 is simply not enough for working
with a lot of virtual systems.... That's why I bumped it that high.

Nevertheless, the current lvm2 version should be able to deal with such slow
scanning processes. I'll try to find out some sane value, sufficient for some
serious virtualization environment, and will try again, if the latest TW
version of lvm2 is then able to deal with it - and activate the VG(s) and LVs.
Will report back with new results when time will permit.