Fibre Channel vs. ISCSI – What to Choose?


Choosing a right storage virtualization solution for your business can be very confusing. Different types of Storage Area Network (SAN) have their own pros and cons. Which technology to choose depends on particular business needs and how much you can afford.

But first it is important to know what makes the difference and what it means to you. Here we'll give you some ideas about two SANs that represent two opposite approaches to storage virtualization. Each with its partisans and opponents, iSCSI and Fibre Channel (FC) cause hot discussions in professional circles. Let's investigate and consider advantages and disadvantages of each.

Advantages and disadvantages of iSCSI and FC

Any SAN uses Hot Bus Adapter (HBA) to connect server to shared block storage array. As the result of such connection, storage network is established that enables a server to exchange data with storage. Various methods can be used to secure storage avaliability and improve its productivity.

Fibre Channel can transfer data using both twisted pair copper wire and optical fiber cables at a speed of 4 Gbit/s. FC is recognized as a В«traditionalВ» SAN, but many IT managers now start giving preference to iSCSI for it is less expensive and complicated. Let's see: you need HBA cards connected to a corresponding port for each server to implement Fibre Channel. This can cost you a considerable amount of money. If you are a small or medium-sized business, such costs can be beyond your strength.

The situation changed in 2003 with ratification of iSCSI protocol based SANs which allowed to send SCSI commands to storage on remote servers. Unlike Fibre Channel, iSCSI doesn't require special cabling. Ethernet LAN technology used by iSCSI is comparatively cheap and easy to learn. At the basic level, iSCSI can produce 1 Gbit/s Ethernet connection that actually can be upgraded to 10 Gbit provided network adapters and switches are adjusted to relevant speed.

However, some believe that iSCSI has low performance when compared to Fibre Channel and thus keep away from deploying this SAN. Experts maintain that iSCSI SANs are likely to face oversubscription and thus become unable to sustain the load. That's why it is recommended to use high-end Ethernet switches for iSCSI networks.

By the way, some FC devices can maintain 10 Gbit speed already and if it goes on this technology will probably attract more users.

Does performance really matter?

According to stats, performance is not a determinal factor when choosing between Fibre Channel and iSCSI. There's a considerable difference in approaches to administration and management of these SANs. As mentionedabove, FC requires peculiar skills and iSCSI can perform poorly on existing TCP/IP protocols. As of now, both technologies remain in parity. And if you have a Fibre Channel SAN, there's no reason why others should not deploy iSCSI and visa versa.