While using secondary service domains help to ensure better availability of guest virtual machines, there are some limitations to using them within an Oracle VM context. The following list outlines each of these limitations that you should be aware of if you decide to configure a secondary service domain:
Clustering: Clustering cannot be used with a secondary service domain. If a server is configured with a secondary service domain then that server cannot be part of a clustered server pool.
Network Configuration: Network bonds/aggregation and VLANs are not automatically configured on the secondary domain. If you configure bonds/aggregation or VLANs on the primary domain using Oracle VM Manager, then corresponding bonds/aggregation or VLANs won't be automatically configured on the secondary domain. If you want to use any such bond/aggregation or VLANs with virtual machines then the corresponding bonds/aggregation or VLANs must be manually configured on the secondary domain.
Storage: NFS, SAS, iSCSI and ZFS volumes accessible only from the secondary domain cannot be used or managed using Oracle VM Manager.
ImportantSecondary service domains cannot access NFS repositories. For this reason, virtual machine I/O to virtual disks is served by the control domain only. If the control domain stops or reboots, virtual machine I/O to virtual disks is suspended until the control domain resumes operation. Use physical disks (LUNs) for virtual machines that require continuous availability during a control domain reboot.
Virtual Machine Disk Multipathing: When assigning a disk to a virtual machine, only fibre channel (FC) disks are configured with disk multipathing through the primary and the secondary domains. NFS, SAS, iSCSI or ZFS disks assigned to a virtual machine are configured with a single path through the primary domain.
Virtual Machine Network Port: When assigning a network port to a virtual machine, two network ports are effectively configured on the virtual machine: one connected to the primary domain, and one connected to the secondary domain. The network port connected to the primary domain is configured with a MAC address that can be defined from within Oracle VM Manager. The MAC address must be selected in the range [00:21:f6:00:00:00, 00:21:f6:0f:ff:ff]. The network port connected to the secondary domain is configured with a MAC address derived from the MAC address of the network port connected to the primary domain. This MAC address starts with 00:21:f6:8.
For example, if the MAC address defined in Oracle VM Manager is 00:21:f6:00:12:34 then this MAC address is used on the network port connected to the primary domain. The derived MAC address is then 00:21:f6:80:12:34 and should be used on the network port connected to the secondary domain. Oracle VM Manager uses a default dynamic MAC address range of [00:21:f6:00:00:00, 00:21:f6:ff:ff:ff]. When using a secondary service domain, this range must be reduced to [00:21:f6:00:00:00, 00:21:f6:0f:ff:ff]. See Virtual NICs in the Oracle VM Manager User's Guide for more information on changing the default range of MAC addresses within the Oracle VM Manager Web Interface.
Live Migration: A virtual machine cannot be live migrated to a server configured with a different number of service domains. That is you cannot migrate a virtual machine running on a server with a secondary service domain to a server without a secondary service domain; and you cannot migrate a virtual machine running on a server without a secondary service domain to a server with a secondary service domain.