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How to increase the maximum queue depth per Logical Unit Number (LUN) in Windows with QLogic MC and Emulex Host Bus Adapter (HBAs)

Applies to

SnapManager for Exchange (200+)
SnapManager for Microsoft SQL Server


After adjusting the HBA queue depth on a QLogic HBA on a Windows 2003 Host, a performance monitoring tool such as Perfmon for Windows reveals that input/output (I/O) from the host to the filer improved on a per HBA basis, but not on a per LUN basis.

After further research:

  • Applications are confirmed to be functioning properly.
  • Filer shows no performance bottlenecks.
  • SAN fabric shows no performance bottlenecks.



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