WDM-FC?
Open Interfaces Pursued For SAN
(02/04/99, 8:09 p.m. ET)
By Loring Wirbel, EE Times
Promoters of storage area networks (SANs)
made two independent efforts this week for
open interfaces operating at several layers in
the SAN protocol stack.
Legato Systems, in Palo Alto, Calif., pulled together
more than 20 vendors in areas such as Fibre Channel
control and systems-management software to support
new open SAN management concepts. Separately,
EMC, in Hopkinton, Mass., and Legato joined several
companies to form FibreAlliance, a group whose
mission includes the drafting of a Storage Network
Management Protocol to present to the Internet
Engineering Task Force (IETF).
Legato, whose NetWorker network-backup product
has become a standard in the LAN community, has
made several efforts to collaborate on SAN standards
in recent months. The company had linked up with
several device vendors in late 1996 to promote open
drivers to the Global Enterprise Management System
environment, then partnered with 3Com and MTI
Technology last November as part of 3Com's bid to
move to SAN environments.
This time around, Legato's partner list covers the gamut
of storage and I/O specialists, including Data
General's Clariion division, StorageTek, 3Com, MTI,
Ampex, Ancor, ATL, ADIC, Compaq Computer,
Computer Networking Technology, Crossroads
Systems, Datalink, Dell Computer, Emulex Network
Systems, Exabyte, Gadzoox Systems, G2 Networks,
Jaycor Networks, Network Appliance, Overland Data,
Qlogic, Qualstar, Silicon Graphics, Sun Microsystems,
Vangard Data, Vixel, Box Hill, and Brocade Systems.
The members of FibreAlliance are EMC, Legato,
McData, Veritas Software, Hewlett-Packard, Ancor,
Emulex, Gadzoox, G2 Networks, Jaycor, Vixel, and
QLogic.
The consortium is the first Legato has worked on since
acquiring two critical companies: FullTime Software,
obtained for its SAN clustering technology; and
Intelliguard Software, which developed the Celestra
embedded data-replication product, and promotes the
Third Party Copy spec for openly transferring data in a
SAN environment.
With the Intelliguard acquisition, announced late in
January, Legato not only can move closer to broad use
of the Third Party Copy protocol, but also marches
behind the Network Data Management Protocol
(NDMP), which Intelliguard is promoting in IETF and
other venues in collaboration with Network Appliance.
Nora Denzel, senior vice president of product
operations at Legato, said that SANs, in theory, will
have the same open suite of protocols for element and
policy management that are now available in LANs and
WANs. In some instances, such as the Intelliguard
Third Party Copy protocol, Legato will promote
proprietary de facto common interfaces, Denzel said,
but in most cases, official standards promulgated by
IETF and ANSI will be the preferred path. The
proposed storage NMP will have open management
information bases, just like the simple NMP that shares
the SNMP acronym. The NDMP plays a
complementary role by insuring interoperability among
file servers and backup systems from different vendors
in implementing heterogeneous network-attached
storage.
The FibreAlliance, announced just weeks after Sun
Microsystems introduced its StoreX initiative, might
appear to represent an overabundance of standards
efforts, but Scott McIntyre, business line manager for
storage networking at Legato, said the efforts are fairly
complementary. FibreAlliance and Legato's own SAN
initiative are driving to common storage-management
interfaces, he said, while Sun's StoreX is attempting to
define a software framework for application
development in storage management. Consequently, it
should be no surprise that many companies are working
with all the groups.
SANs traditionally are defined by their use of block
protocols that are more efficient for moving data in and
out of storage than the TCP/IP protocols used in data
networks. But the seven layers of the simpler
message-passing SANs are slowly adopting much of
the richness of the Open Systems Interconnect stack for
LANs and WANs. Denzel said it should be no surprise
in a few years to see self-healing, protected SANs,
possibly scaling to wide-area dimensions, with full
policy-management control of the type seen in Layer
4-7 LAN/WAN switches.
In fact,with the advent of wave-division multiplexing on
Fibre Channel, proposed as a vehicle to bring
public-network carriers into SAN management, the
alliances have to consider scaling management tools to
service providers. Greg Beyer, CEO of Fibre Channel
switching specialist Brocade Communications, said that
"it doesn't require a huge leap of faith" to see switched
Fibre Channel meshes being connected over public
backbones. SAN management as a carrier service will
be feasible given updates in routing algorithms and
restoration concepts, he said, but the business model
needs to develop further before Brocade or other
companies are likely to offer management tools for
carriers.
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