• Backup storages are disconnected. Verify that these backup storages are available and normally connected.
• Primary storages have not attached any cluster. Therefore, available hosts are not found. Verify that these primary storages have attached clusters.
• No available hosts in clusters satisfy instance offerings. Verify that hosts are available and have sufficient resources.
• Capacities for primary storages are insufficient to provide virtual capacities required by images. Verify that these capacities of these primary storages are sufficient.
• Clusters have not attached the corresponding networks. Verify that these clusters have attached the corresponding networks.
• Resources of an IP address pool are insufficient. Verify that IP ranges are sufficient.
• The links between backup storages and primary storages are abnormal. Verify that the links where images are downloaded to these primary storages from these backup storages are normal.
• The dnsmasq service of the distributed DHCP service in hosts are abnormal. Verify that the DHCP service can automatically assign IP addresses to VM instances.
• The libvirtd service of hosts are abnormal. Verify that the libvirtd service is normal so that it can provide virtualization.
• If a VM instance keep enabling, check whether the image of this VM instance is huge and whether downloading image caches is time-consuming. If these image caches exist, continue to check /var/log/zstack/zstack-kvmagent.log of the host where the VM instance resides.