- Why should SMBs look at iSCSI vs. Fibre Channel (FC) SANs?
- iSCSI SANs are less expensive than FC SANs.
- An iSCSI SAN is based on the familiar and ubiquitous TCP/IP protocol.
- iSCSI SANs are less complex and easier to manage than FC SANs.
- How can iSCSI save you and your customers' money?
iSCSI uses TCP/IP instead of a proprietary storage protocol such as FC. As a result, iSCSI SANs can be built with commodity network components, eliminating the need for costly FC host bus adapters (HBAs), which are typically priced between $800 and $1,200, and FC switches.
- How is iSCSI being used in SMBs vs. large enterprises?
While SMBs use iSCSI SANs as their primary storage, large enterprises use iSCSI to complement their FC storage for less mission-critical departmental apps, remote offices and data protection. Typical applications for iSCSI are messaging apps like Microsoft Exchange, databases, Web apps, file serving and disk-to-disk backup.
- What iSCSI weaknesses should you consider when developing iSCSI services offerings?
Storage management is one of the weaker aspects of iSCSI. Storage management vendors are just starting to add iSCSI support to their suites. While FC switches are well supported by all
- major storage management apps, only some aspects of Ethernet switches, like availability, are addressed by storage management suites.
Security is another controversial aspect: Although FC proponents are quick to point out security concerns with iSCSI, in reality, iSCSI is an inherently more secure protocol than Fibre Channel.
With the reliability and feature gap closed, the slower performance of iSCSI is now the primary technical argument FC advocates use for not considering iSCSI for enterprise-level applications. But iSCSI speeds are beginning to catch up with FC, and the two protocols are on a leap-frog path with each one boasting new product releases that bests the other, but not for very long. However, the FC protocol has a slightly lower latency than TCP/IP.
- Why iSCSI, why now?
One could argue that the popularity of NAS was the main reason for the ever-increasing interest in iSCSI. NAS dependency on higher level file-system protocols (CIFS/NFS) makes NAS less suitable for block-based transactional applications like databases; as a result, NAS vendors are adding iSCSI support to their offerings. Because NAS and iSCSI are both based on TCP/IP, iSCSI is a more natural SAN supplement than FC in NAS environments.
Furthermore, the number of innovations and companies developing for the TCP/IP and iSCSI space today greatly surpasses the number of FC developments. Besides 10GigE, network packet processors--from companies like Broadcom Corp. and Cavium Networks--for packet inspection, prioritization, encryption, compression and TCP optimization are the building blocks for next-generation TCP/IP and iSCSI products.
- Will iSCSI push FC out of the data center?
There's no doubt iSCSI will dominate the SMB storage space and will be the preferred storage option for workgroup servers and, eventually, corporate desktops. What's still unclear is if iSCSI can push FC out of the enterprise data center. With FC's large installed base, long-standing support for mission-critical apps and the availability of 8Gb/sec FC, it's the preferred technology for most large data center storage. For a transition to happen, it will take large storage vendors like EMC, HP and IBM to recommend iSCSI over FC, which is unlikely to happen in the near future.