Error occurred when tried to power cycle spu and virsh destroy :

[nz@netezza2 ~]$ nzpush -s 1/2 power cycle
Powering cycle SPUs spu0102 ....error: Failed to connect socket to '/var/run/libvirt/libvirt-sock': Connection refused
error: failed to connect to the hypervisor Failed to power cycle SPUs spu0102

[root@netezza1 ~]# virsh destroy spu0102
error: Failed to reconnect to the hypervisor
error: no valid connection
error: Failed to connect socket to '/var/run/libvirt/libvirt-sock': Connection refused

 This can be fixed by checking libvirtd service status.  
 In this case, the service was in dead state  
 After the libvirtd service stopped and started, the issue got fixed.  

[root@netezza1 ~]# /etc/init.d/libvirtd status
libvirtd dead but pid file exists

[root@netezza1 ~]# /etc/init.d/libvirtd stop
Stopping libvirtd daemon: [FAILED]

[root@netezza1 ~]# /etc/init.d/libvirtd start
Starting libvirtd daemon: [ OK ]