Using multiple iSCSI HBAs for redundancy

Even if the bandwidth requirements of a server do not indicate that more than one iSCSI HBA for iSeries™ is needed, you may want to use multiple iSCSI HBAs to provide fault tolerance and redundancy. This will reduce the likelihood of server failures that are caused by a failure of an iSCSI HBA or one of the network components (switches, cables, and so on.) that connect the iSeries to the hosted system. Redundancy is provided by the iSCSI ability to do multi-path I/O (see Advanced iSCSI support). To take advantage of multi-path I/O, you create a multi-path group that identifies two or more iSCSI HBAs. Then you define which virtual disks will use the multi-path group. You can optionally use the multi-path group as the default path when linking disk drives.

To define a multi-path group using iSeries Navigator, first shut down the server (see Start and stop an integrated server), then follow these steps:

1. Expand Integrated Server Administration.
2. Expand Servers.
3. Right-click a server from the list available.
4. Select Properties.
5. Click on the Storage Paths tab.
6. Define at least two storage paths (use the Add button, if necessary).
7. Below the storage paths table, click the Properties button for the multi-path group.
8. Use the checkboxes to identify two or more of the defined storage paths to be members of the multi-path group.
9. Click OK to update the multi-path group information on the server properties panel.
10. Optional: Select the multi-path group as the default path for disk drives.
11. Click OK on the server properties panel to save the changes in the NWSD.

If you want to use a CL command, see the MLTPTHGRP and DFTSTGPTH keywords on the CHGNWSD command.

Now that the multi-path group is defined, you need to re-link one or more of the server's virtual disks in order to use the multi-path group. First unlink the disk (see Unlink integrated Windows server disk drives). Then link the disk to the server again (see Link a disk drive to an integrated server), specifying either the multi-path group explicitly or specifying the default path (if the default path for disk drives was defined to use the multi-path group).