Hi, I grabbed today's git head of libvirt. Created a VM (clean install of ubuntu oneiric, installed through virt-manager), and cloned it 3 times. Then I did serge@ubuntu:~$ for i in `seq 1 4`; do virsh start o$i > /tmp/o$i 2>&1 & done [1] 12184 [2] 12185 [3] 12186 [4] 12187 serge@ubuntu:~$ virsh list error: Failed to list active domains error: End of file while reading data: Input/output error serge@ubuntu:~$ virsh list Id Name State ---------------------------------------------------- 5 o2 shut off 7 o3 shut off 8 o4 shut off [1] Exit 1 virsh start o$i > /tmp/o$i 2>&1 [2] Done virsh start o$i > /tmp/o$i 2>&1 serge@ubuntu:~$ virsh list Id Name State ---------------------------------------------------- 5 o2 running 7 o3 running 8 o4 running [3]- Done virsh start o$i > /tmp/o$i 2>&1 [4]+ Done virsh start o$i > /tmp/o$i 2>&1 serge@ubuntu:~$ cat /tmp/o1 error: Failed to start domain o1 error: Unable to wait for child process: Bad file descriptor It's quite reproducible. An ubuntu bug report was filed at https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/961217 It's also very reminiscent of some lxc startup handshake issues which have been fixed. You can find the last chunk of the log file at http://people.canonical.com/~serge/libvirtd-parallel-startup.log -serge