iSCSI products
Cisco Systems and IBM are among the biggest backers of iSCSI and have worked hard to develop it. The companies have even begun shipping products with early versions of iSCSI.
One of the hurdles for the technology's adoption was the IETF's requirement that iSCSI include support for a technology called IPsec, which permits encrypted communications. IPsec support threw a wrench in the works of companies such as Adaptec that planned to build special-purpose microprocessors that speed up the communications that underlie iSCSI.
"iSCSI chipsets will eventually include support for IPsec in them," says Doug Ingraham, senior manager for Cisco's SN 5400 line of iSCSI storage switches. In the meantime, Cisco will support iSCSI's IPsec by packaging it with a separate networking system, he said.
Some others are supporting the IPsec with software, a route that is sluggish compared to special-purpose chips, but not necessarily that big a problem because customers aren't clamouring for IPsec at this point, Ingraham adds.
Cisco recently began including Fibre Channel communication capabilities in its SN 5428 iSCSI switch. In August, Cisco introduced its MDS 9000 switch, a higher-end system that supports dozens of iSCSI and Fibre Channel ports.
iSCSI considerations
- Reliability: The IP infrastructure that iSCSI relies upon has a proven transport track record, so companies can move data to storage over it with confidence.
- Pooled storage: Unlike some solutions that create isolated data repositories, iSCSI can create shared storage. Users will thus be able to connect multiple storage devices to multiple servers to expand storage and streamline storage management.
- Data storage over great distances: Data can basically be stored efficiently anywhere that Internet access is available. Users will have remote access to sites potentially spread over a wide geographic area, which opens up a number of storage and data backup options. Users will be able to store and access data no matter where they are.
- Performance: iSCSI promises to improve performance by offering block-level access to data rather than file-level access. Performance will also be enhanced by offloading some of the SCSI processing to the NIC.
- At the time of writing, the iSCSI specification had been finalised but not ratified by the IETF. Some people counsel caution until any interoperability issues have been settled.
- iSCSI uses relatively cheap gigabit Ethernet links between servers and storage devices, providing the benefits of consolidated storage without the cost of Fibre Channel.
- Gigabit Ethernet is a technology familiar to most organisations, whereas Fibre Channel expertise is not so widespread.
- The low cost of iSCSI makes it affordable to connect second-tier servers to consolidated storage, and allows smaller organisations to enjoy the benefits of a SAN.
- A network accelerator card (NAC, or TOE) will often be needed to take the load off a server's CPU.
- iSCSI can be used for local or long-haul connectivity.
- Broad adoption is not expected until 2003-2004, by which time it is likely that enterprise-class storage units will offer the option of iSCSI connectivity.
- Check your software works with iSCSI—it should, but don't just assume everything will be OK.
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