A Storage
Area Network (SAN) provides an interconnect
infrastructure between storage devices and their clients (typically,
application servers). In the past, every server had its own private
storage. This meant that storage was scattered over a large number
of servers, which complicated storage management and administration.
SANs allow clients to share storage, making it easier for
administrators to manage a storage pool. This advancement was made possible
largely because of the application of networking technology to
storage, allowing clients to access network-attached storage in the
SAN.
Currently, the networking technology in SANs is based on a
specialized technology called Fibre Channel. The question arises
whether we can use the networking technology of the Internet
-- the TCP/IP stack -- for storage. IP SANs could leverage the
prevalent technology in the Internet to scale from the scope of a
LAN to a WAN, thus enabling newer classes of storage applications.
Moreover, an IP SAN would also seamlessly benefit from new
networking developments on the Internet such as QoS and security. It
is also expected that the cost of ownership of IP SANs would be
lower due to larger volumes and a more widely-skilled manpower base.
The challenge is that the networking paradigm is based on design
considerations different from those of the storage paradigm. This
leads us to ask: Is it possible to merge the two paradigms and yet
provide the performance of a specialized storage protocol?
To
this end, we have designed and developed the industry's first iSCSI
storage controller - the IBM TotalStorage IP Storage 200i, which boasts of a
performance of 105 MBps throughput and 500 usec latency. The product
was generally available in June 2001 and received wide industry attention. In
addition, our implementation has performed exceptionally well in
interoperability plugfests and has become a de facto reference
platform. Simultaneously, we are also working to ratify the iSCSI
standards.
The
IETF iSCSI Standards
Download
a comparative analysis of SAN technologies paper.
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