IP-SAN, the networked storage wave-of-the-future?

Computer Technology Review, June-July, 2005 by Ed Ginty

Interoperability

Internet SCSI (iSCSI), an industry standard was developed to enable transmission of SCSI block-commands over existing IP networks by using the TCP/IP protocol. iSCSI offers organizations the possibility of delivering both messaging traffic and block-based storage over existing Internet Protocol (IP) networks, without having to install a separate Fibre-Channel network.

iSCSI Advantages

Long-distance connectivity

Fibre-Channel SANs installed in organizations with offices distributed over wide areas could possess unlinked "SAN islands" that cannot be bridged past 10km. Although there are new ways to extend Fibre-Channel connectivity up to several hundred kilometers, these can prove complex and costly. iSCSI over WAN (Wide Area Network) provides cost-effective long-distance connectivity that can be used as a bridge to existing Fibre Channel SANs or between native iSCSI SANs. This utilizes in-place MANs (Metro Area Network) and WANs.

Lower costs

Unlike Fibre-Channel solutions that require a completely new network infrastructure, solutions such as clustering are simpler with iSCSI than with Fibre-Channel. iSCSI SAN solutions capitalize on preexisting LAN infrastructure and utilize the IP expertise already available within most organizations.

Simple use implementation and management.

iSCSI solutions require little more than the use of the Microsoft iSCSI initiator on a host server, a target iSCSI storage device and a Gigabit Ethernet switch to deliver block level storage over IP. Managing iSCSI devices for storage configuration, provisioning and backup can be easily handled by the system administrator similar to how such operations are handled for DAS.

An Analysis of the Costs--DAS (Direct Attached Storage) vs. iSCSI SAN vs. Fibre-Channel SAN

There are two types of costs associated with purchasing new storage. The first, hard/direct costs bears directly on the IT budget and includes capital spending, labor, outsourcing, professional services, support contracts and training. The second, soft costs, are less tangible and are often hidden. They include, loss of productivity or lost business revenue when a system goes offline for upgrades, repairs or to accommodate a large backup window. Both must be considered in order to accurately calculate the total cost of ownership (TCO). Based on deploying a 2 Terabyte SAN with backup using industry average list prices, iSCSI SANs can be less than half the cost of Fibre Channel technology with ongoing management cost savings. iSCSI also provides up to a 60 percent savings in storage administration costs compared to equivalent capacity DAS.

Summary

In the end, IT/financial decision makers must decide which solution(s) meets their exact requirements for performance, reliability, scalability and cost. Sometimes, the best solution utilizes multiple vendors' technologies, configured in a complementary fashion in order to solve several separate problems. The advice this author offers to clients who inquire about which networked storage technology is best for them is that they do their homework to learn the details of what each technology offers and then apply the technology that best fits their budget and unique current and future storage growth needs. The last thing anyone wants to have to do is to forklift out a solution they already invested heavily in just because their organization's data requirements continued to grow and what they had implemented could not keep up with the growth.