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|InfiniBand simplifies server I/0|
Ever since iSCSI appeared on the horizon, the hype has been deafening. Initial iSCSI enthusiasts boasted it would rule the storage area network (SAN) world, and FC would just become another victim of Ethernet road kill. That was two years ago. The claims today aren't nearly as brash and have attempted to focus on more realistic value propositions. Examining the value propositions requires a closer examination of the technology itself.
iSCSI is a block storage transport protocol - it takes the common block storage SCSI-3 protocol and maps it to TCP/Ip. This allows it to be enveloped in Ethernet packets and transported over standard LAN/WAN infrastructures. iSCSI is designed to allow block storage SANs to be deployed on IP networks.
iSCSI value propositions
iSCSI was designed to solve negative FC perceptions such as FC's high cost, complexity and interoperability issues. The proposed value propositions for iSCSI are:
1. Reduction or elimination of SAN professional service costs - the SAN is based on the same Ethernet technology most organizations already have, with a large pool of knowledge workers.
2. Lower SAN hardware costs because of lower cost copper cabling for Gigabit Ethernet (GigE) and 10/100, as well as lower switch and interface costs.
3. Faster SAN deployments requiring less IT staff time because of the Ethernet familiarity.
4. Simpler SAN management - iSCSI SANs utilize the well-known TCP/IP and Ethernet management tools.
5. Elimination of interoperability issues because of the reuse of Ethernet technologies and the tight standards of the Internet Engineering Task Force (IETF).
6. Elimination of multiple fabric infrastructures for client server and block storage - both will run on the same technology even if they require separate networks.
7. Elimination of distance boundaries for SANs because IP networks have no distance boundaries.
8. Equal or better performance vs. FC SANs.
So how valid are these value propositions?
Reduction or elimination of SAN professional services. The premise of this value proposition is that most SAN professional services are tied to FC setup and management, but that's only partially true. A key factor in the SAN setup is the upfront work with the SAN assessment. The SAN assessment determines which initiators (applications and servers) go to which targets (storage volumes), and how much storage each initiator needs. iSCSI professional services can potentially reduce the SAN setup. Most FC SANs require fairly complex zoning setups - QLogic being the exception. This would be eliminated in an iSCSI SAN and be replaced by VPNs, which are easier to setup. The value proposition accuracy: medium.
This was first published in October 2002