8.3 IP Storage Network Scenarios

The IP storage model can be applied to a wide range of scenarios. In this section, we explore some typical SAN applications. In the following section, we explore actual case studies that carry the IP storage model further with distributed storage intelligence and functions.

The three IP storage network scenarios covered, SAN extension, storage consolidation, and service provider SANs, all overlay onto the concentric circles of the IP storage model. In each case the IP core represents a different element of the universal IP network. For SAN extension, the IP core is the metro-area or wide-area IP link connecting the remote sites. For storage consolidation, the IP core might be redundant enterprise Gigabit Ethernet switches. For service provider SANs, the IP core is the high availability metro Ethernet network. The multidimensional approach and broad applicability of the IP storage model presents strategic cost savings across a portfolio of IT projects.

IP storage networking, particularly in the context of metro-and wide-area networking options, is covered more thoroughly in Chapter 9, "Assessing Network Connectivity."

8.3.1 SAN Extension

SAN extension fits most corporations' needs for remote mirroring, backup, and recovery. Typically, to guarantee availability in the event of a site disaster, the remote location is several kilometers away at a minimum, though up to hundreds and thousands of kilometers is not uncommon. A conventional approach of connecting two Fibre Channel SANs natively has limitations in that the link must be dedicated fiber- optic cabling and cannot take advantage of the IP core.

Implementing an IP storage connection using intelligent storage nodes such as IP storage switches or gateways allows customers to leverage existing IP cores for remote connectivity. The IP core may be in the form of a dedicated or provisioned metro-or wide-area IP network. Figure 8-8 depicts an IP core for remote mirroring applications.

Figure 8-8. Using IP networking for SAN-to-SAN remote mirroring.

Use of an IP core for remote mirroring benefits TCO and ROI in the following ways:

• Familiar IP and Ethernet management tools for IP networks lead to lower training costs.

• More IP and Ethernet components lowers hardware costs for end users.

• Centralization on IP core enables migration path to new IP storage deployments.

• Robust IP security and encryption tools protect mission-critical data.

8.3.2 Storage Consolidation

Another common SAN application is storage consolidation, which provides the benefits of pooling storage resources together for sharing, centralized management and administration, and addition and removal of resources. With isolated storage islands, each server group has dedicated storage resources. Dedicated resources lead to high management costs and poor scalability and availability of storage and servers. This type of configuration can easily lead to server and LAN bottlenecks, and single points of failure.

Storage consolidation using an IP storage model allows companies without extensive Fibre Channel resources to make maximum use of their IP infrastructure. In this case, as shown in Figure 8-9, a customer could deploy Gigabit Ethernet switches as an IP core, surrounded by iSCSI and Fibre Channel storage access nodes. Protocol conversion can easily be provided by IP storage switches or gateways. This scenario provides massive consolidation on an IP storage fabric.

Figure 8-9. Using an IP core for storage consolidation.

Use of an IP core for storage consolidation benefits TCO and ROI in the following ways:

• Single enterprise focus simplifies management and administration costs.

• Network consolidation leverages existing IP and Ethernet resources and staff.

• Consolidation reduces overall storage amount and perhaps some servers.

• Use of additional IP and Ethernet components lowers TCO in hardware and software.

8.3.3 Service Provider SANs

Chapter 7, "Options for Operational Agility," covered the benefits of using storage service providers to maximize operational efficiency. In many cases, companies create the services and offerings of a professional provider at a similar cost. It therefore frequently pays to outsource some portion of the storage infrastructure.

Before block-based IP storage networks emerged, most service providers were restricted to parceling out customer storage on a SAN-by-SAN basis. This could involve dedicated links between each customer and the service provider. Since the availability and cost of dedicated fiber-optic cabling makes this difficult in metropolitan areas, most SSPs offered services within collocation facilities.

Using widely available IP networks, SSPs can take advantage of relatively inexpensive bandwidth to offer a variety of storage services. The multiple customer configuration is shown in Figure 8-10.

Figure 8-10. Metropolitan area IP connectivity for outsourced storage services.

Use of an IP core for service provider SANs benefits TCO and ROI in the following ways:

• Readily available IP bandwidth saves provider and end- user costs.

• IP infrastructure can be easily partitioned, allowing multiple customers to be segmented within one network.

• The IP network makes use of Open Shortest Path First (OSPF), Border Gateway Protocol (BGP), and autonomous regions for maximum scalability.