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That Storage Area Networks (SANs) are grabbing IT planners' attention is not difficult to understand, if you consider that the main IT focal point has become how to make the move toward delivering information and keeping it available. Data has become an entity unto itself, dissociated from any specific server. Without proper management, this data entity can become an IT planning nightmare. Enter Storage Area Networks. SANs connect distributed data islands into highly accessible and reliable information resources. But the SAN is still a young architecture. Difficult issues cloud its deployment, especially on Linux.
Where are Linux-based SANs? I recently asked the world's largest storage manufacturer, EMC, to introduce me to any customer that has installed a Linux-based EMC SAN. EMC had a difficult time finding a qualified candidate. Linux installations in general are growing at twice the rate of Windows 2000 installations, but the adoption rate for Linux-based SANs is many times less than that of Windows 2000 or any other Unix variant, such as Solaris.
How can this be, with Linux becoming the OS of choice in many enterprise environments? Having entirely Linux-based SANs may still be a dream, because SAN vendors have not fully adopted Linux as a viable product platform. Storage vendors are reluctant to port to Linux because storage organizations cannot agree on interoperability standards between operating systems and SAN protocols.
A SAN removes storage traffic such as backup data from the production network and puts it on a dedicated storage network. This act decreases a production network's overall load while increasing application availability. A SAN is designed to handle traffic independently from the LAN or WAN. The server is connected to the SAN through a back-end Fibre Channel (FC) connection, which provides the high-performance transfer rate and distance remote servers need. SANs let IT planners proactively allocate logical storage to servers.
Storage organizations such as SNIA and the Fibre Channel Alliance have had the task of creating SAN standards. One big debate in the SAN community is whether FC or Ethernet will be the standard SAN
protocol. For now, FC and Ethernet must coexist. SAN vendors and customers need to choose which protocol they want. The debate for a standard SAN protocol has also resulted in different manufacturers making products that do not interoperate. This situation has triggered allegiances within the community, with companies squaring off against each other in the race to be the first to set standards.
Microsoft sees Linux as its biggest threat for the foreseeable future. Sun Microsystems will only support Solaris on its server systems. Relationships with these companies have prevented SAN vendors from fully committing to Linux. Unfortunately, Linux does not have a strong organization championing its cause in the SAN community. Why manufacturers have done anything at all for Linux is because of the many loyal users. SAN vendors are walking a fine line between providing just enough functionality or fully supporting Linux.
The standards hurdle will take some time to work out, with splintered agendas coalescing into better times for all. But as the proliferation of Linux increases-and if a powerful Linux SAN champion emerges-the idea of Linux SANs outpacing all other types of SANs may not be a dream after all.
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