[libvirt-users] domain has active block job

Hi there, I receive this error when I run nova image-create <VM name> <Vm Sanpshot name>: Exception during message handling: block copy still active: domain has active block job In libvirt log file I can see: error : qemuDomainDefineXML:6312 : block copy still active: domain has active block job Libvirt is 1.2.7 version, linux system is Debian Wheezy Please, what does it mean ? Regards Fiorenza -- Spazio Web S.r.l. V. Dante, 10 13900 Biella Tel.: +39 015 2431982 Fax.: +39 015 2522600 Numero d'Iscrizione al Registro Imprese presso CCIAA Biella, Cod.Fisc.e P.Iva: 02414430021 Iscriz. REA: BI - 188936 Cap. Soc.: €. 30.000 i.v.