Chapter 1 Before Configuring SN 5428-2 Storage Router Software
Transparent SCSI Routing Overview
For example, if an iSCSI target were created for WWPN 3100112233445566 in a storage array, and that WWPN contained LUNs 0 through 2, those LUNs would become available to an IP host as LUNs 0 through 2. An iSCSI driver would see the iSCSI target named eui.3100112233445566 as a controller with three iSCSI LUNs identified as LUN 0, LUN 1, and LUN 2. Each iSCSI LUN would appear as a separate storage device to an IP host.
Mapping each IP host to a Fibre Channel address consists of assigning a WWPN to an IP host that is requesting access to storage; the WWPN is used for presenting the IP host as an FC host to a storage array. The SN 5428-2 maintains a pool of 62 WWPNs that are assigned to IP hosts requesting access to storage. When an IP host is granted access, a WWPN is assigned to the IP host and the SN 5428-2 presents the host as an FC host to the storage array. That host continues using that WWPN until it is finished using the storage. When transparent SCSI routing is deployed in dynamic mode, once the host is finished using the storage (logged out), the WWPN becomes available for assignment to other IP hosts requiring access to storage. In static mode, the IP host/WWPN mapping is retained throughout IP host logins and logouts and throughout storage router reboots.
See Table 1-4for an example of transparent SCSI routing mapping. In this mapping example, the WWPN, 200100023D000100, is assigned to the IP host. Using that WWPN, the SN 5428-2 presents the IP host as an FC host to the storage array. Three devices are made available as local storage devices: Local Disk (E:), Local Disk (F:), and Local Disk (G:). (Microsoft Windows devices are used as examples.) The iSCSI target, eui.3100112233445566, has been automatically created and mapped to a WWPN, 3100112233445566, that was made available by the storage array. To the IP host, the iSCSI target appears as a controller with LUNs 0, 1, and 2 available. The LUNs are apparent as they are with the WWPN in the storage array.
Table 1-4 Transparent SCSI Routing Mapping Example
| | | LUNs | | |
| | | Apparent | | Physical |
WWPN assigned to IP | Apparent to IP | | with iSCSI | WWPN of Storage Array | LUNs |
Host | Host | iSCSI Target Name | Target | Target | Available |
| | | | | |
200100023D000100 | Local Disk (E:) | eui.3100112233445566 | LUN 0 | 3100112233445566 | LUN 0 |
| | | | | |
| Local Disk (G:) | eui.3100112233445566 | LUN 1 | 3100112233445566 | LUN 1 |
| | | | | |
| Local Disk (H:) | eui.3100112233445566 | LUN 2 | 3100112233445566 | LUN 2 |
| | | | | |
Access for transparent SCSI routing is controlled in the IP hosts and the intelligent storage array. In an IP host, the iSCSI driver is configured with the Gigabit Ethernet IP address of the SCSI routing instance in the storage router with which the host is to transport SCSI requests and responses. In the intelligent storage array, access is controlled through its storage management tools. Additionally, access can be further controlled in the SN 5428-2 through authentication. See the “Authentication Overview” section on page 1-24for more information about authentication.
Once the access is configured in the hosts and the intelligent storage array, the SN 5428-2 transparently routes SCSI requests and responses between hosts and the mapped storage devices.
Figure 1-13represents the concept of storage mapping and access control for transparent SCSI routing. In the figure, the SN 5428-2 Storage Router provides three IP hosts with access to disk drives made available by the intelligent storage array. A single SCSI routing instance in the storage router is configured with IP address 10.1.2.3 for the Gigabit Ethernet interface. The iSCSI driver in each IP host is configured to access that SCSI routing instance by its IP address 10.1.2.3 through the Gigabit Ethernet interface on the storage router. From the perspective of an IP host, each disk drive mapped to it appears as a locally attached disk drive. From the perspective of the storage array, each host is connected directly
Cisco SN 5428-2 Storage Router Software Configuration Guide
