Network server description

The network server description (NWSD) object shown in Figure 15 is basically the same as described for Figure 14 except for the following:

• It contains a reference to a remote system configuration object instead of an iSeries™ hardware resource name.
• Unlike an IXA attached server which uses one IXA card in the xSeries® system to manage all of the SCSI and virtual Ethernet data flows, on an iSCSI attached server solution both the iSeries and the xSeries can have multiple iSCSI host bus adapters (HBAs). This allows multiple SCSI and virtual Ethernet data paths between the iSeries and xSeries or IBM® BladeCenter™ systems, which can provide greater bandwidth and connection redundancy.
• You can define one or more storage paths. These storage paths reference the NWSH objects that are associated with the iSCSI HBAs that are used by the integrated server. You can choose which storage path is used for the SCSI data flows for each virtual disk drive. By associating your virtual disk drives with different storage paths, you can spread the overall server SCSI data flow workload across the storage path iSCSI HBAs for greater bandwidth.
• You can define a multi-path group, which is a subset of the configured storage paths. You can then associate a virtual disk drive with the multi-path group, instead of associating it with a specific storage path. Using the multi-path group for a virtual disk drive has the advantage that if the iSCSI HBA for one of the NWSHs in the multi-path group fails or the network connection to the iSCSI HBA fails, the SCSI data flow workload for that virtual disk drive is automatically routed to one of the other iSCSI HBAs that is configured in the multi-path group. This provides connection redundancy and improves availability.
• You can define one or more virtual Ethernet paths. These virtual Ethernet paths also reference the NWSH objects that are used by the integrated server. You can choose which NWSH is used for each virtual Ethernet port that the integrated server uses. By associating different virtual Ethernet ports with different NWSHs, you can spread the overall server virtual Ethernet data flow workload across the virtual Ethernet path iSCSI HBAs for greater bandwidth.
• Just as with an IXS or IXA attached server, the iSCSI attached xSeries or IBM BladeCenter server hardware is controlled by i5/OS™.
  • An iSCSI attached server is started and shut down the same as with an IXS or IXA attached server (see Figure 14), by varying on or off the NWSD for that server.
  • For an iSCSI attached xSeries or IBM BladeCenter server, i5/OS communicates over an Ethernet network with the service processor (SP) for the xSeries system or the IBM BladeCenter management module for an IBM BladeCenter server to perform the start and shut down tasks.

  For server hardware power control, the main difference between the IXS/IXA configurations and the iSCSI configuration is that for IXS or IXA attached servers, the server hardware is identified by the iSeries hardware resource name, while for iSCSI attached servers, the server hardware is identified by the remote system configuration object.

  Note:
  Since the xSeries or IBM BladeCenter server that an iSCSI that an iSCSI attached server runs on is simply defined via the remote system configuration name in the NWSD, it is easy to switch the hardware that an iSCSI attached integrated server runs on. By changing the remote system configuration name, the xSeries or IBM BladeCenter server that the existing NWSD is booted on can be hot spared. For more information, see Hot spare between server hardware.