Hi, My nova-compute nodes was running libvirt 0.9.13 and QEMU 1.0, after libvirt was upgraded to 1.2.2, the VMs launched by libvirt 0.9.13 can't attach volume any more, i.e. "nova volume-attach <vm-uuid> <volume-uuid>" doesn't work. But before the libvirt upgrade, the same VM can attach volume disk. I did some debuging and find that, it failed in QEMU when try to open the volume device, and the return errno is EPERM. QEMU instances is running as user libvirt-qemu always, so is that possible some problem in Linux capabilites or libvirt apparmor? ------------------------------------- int qemu_open(const char *name, int flags, ...) { int ret; int mode = 0; long euid, egid; if (flags & O_CREAT) { va_list ap; va_start(ap, flags); mode = va_arg(ap, int); va_end(ap); } euid = (long)geteuid(); egid = (long)getegid(); #ifdef O_CLOEXEC ret = open(name, flags | O_CLOEXEC, mode); #else ret = open(name, flags, mode); if (ret >= 0) { qemu_set_cloexec(ret); } #endif return ret; } Regards, CY.