Plan for your external storage system configurations through Fibre Channel connections with Lenovo Storage V series clustered systems.
All Lenovo Storage V series nodes in a system must be able to connect to the same set of storage system ports on each device. A system that contains any two nodes that cannot connect to the same set of storage-system ports is considered degraded. In this situation, a system error is logged that requires a repair action. This rule can have important effects on a storage system such as an IBM® DS4000™ series controller, which has exclusion rules that determine to which host bus adapter (HBA) worldwide node names (WWNNs) a storage partition can be mapped.
A storage-system logical unit (LU) must not be shared between the system and a host.
You can configure certain storage systems to safely share resources between the Lenovo Storage V series system and direct-attached hosts. This type of configuration is described as a split storage system. In all cases, it is critical that you configure the storage system and SAN so that the Lenovo Storage V series system cannot access logical units (LUs) that a host or another Lenovo Storage V series system can also access. This split storage system configuration can be arranged by storage system logical unit number (LUN) mapping and masking. If the split storage system configuration is not guaranteed, data corruption can occur.
Besides a configuration where a storage system is split between a Lenovo Storage V series system and a host, the Lenovo Storage V series system also supports configurations where a storage system is split between two Lenovo Storage V series systems. In all cases, it is critical that you configure the storage system and SAN so that the Lenovo Storage V series system cannot access LUs that a host or another Lenovo Storage V series system can also access. You can use storage system LUN mapping and masking to arrange for this configuration. If this configuration is not guaranteed, data corruption can occur.
When a storage system is detected on the SAN, Lenovo Storage V series attempts to recognize it using its Inquiry data. If the device is not supported, the system configures the device as a generic device. A generic device might not function correctly when it is addressed by a Lenovo Storage V series system, especially under failure scenarios. However, the system does not regard accessing a generic device as an error condition and does not log an error.Managed disks (MDisks) that are presented by generic devices are not eligible to be used as quorum disks.