On one of our storage projects, we are looking at the possibility of expanding the first successful SAN installation and setting up multiple SANs at different sites with at least one across the Atlantic.What are the key issues to look out for at this stage? Also, any idea on how many networks of SANs are currently installed here in the U.S.? Is this a growing trend?
* A leased dark fibre connection through a Telco
* A Dense Wave Division Multiplexed link (DWDM)
* An iSCSI link through an iSCSI gateway over IP
* An IP link using either the FCIP or iFCP protocols The link you choose will be based on your budget, the distance between sites, the bandwidth required and the switch count within each fabric at each SAN island. If you are trying to tie together two fabrics into one bigger one, you need to also be concerned with naming conventions. If you have the same zone name or alias name being used in both fabrics, the fabrics will segregate and you will not be able to merge the fabrics. If you have many switches at each site and use a SAN extender that uses a tunneling protocol like FCIP, you will be creating one large fabric and all error traffic and re-configuration will be propagated across the link. iFCP will connect two SAN islands, while keeping all error traffic isolated within each SAN island. iFCP will allow you to connect up many SAN islands without worrying about errors or re-configuration issues. I will be doing a webcast on the SearchStorage.com site in the very near future that discusses all these issues in much greater detail. You can also get more information from chapters 6,7 and 8 of my book "Storage Area Networks for Dummies." Chapter 8 discusses "networking SANs" in detail.
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This was first published in June 2003