There are two SCSI driver standards that are available for most SCSI HBA’s. The older standard (SCSIport) has been replaced by a newer technology (STORport). STORport allows faster I/O, duplexing and other advantages. You should use the STORport drivers for all HBA’s when available. This is especially revelant for FC cards. The details are: [more]
Classic SCSI (SCSIPort):
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commands were queued on an adapter/LUN basis
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Maximum number of I/O's per adapter is 256, with 16 LUN's per adapater
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Queue limit on LUN level, with a maximum of 20 outstanding I/O's
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If one LUN reaches it's limits all other LUN's will be blocked as well
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Will remain for direct attached storage
Storport:
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No limitation on adapter queues
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Each LUN has a queue limit of 256 outstanding I/O's
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Designed for Fibre Channel attached storage
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Exchange and SQL will probably not be using Storport directly
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Except for SQL RAW disk functionality which will bypass volume management (for higher performance)
More details: http://download.microsoft.com/download/5/6...eb/Storport.doc