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oversubscribed

 

Oversubscribing
 
Some people assume a single subsystem port maps to a single LUN when in reality there are usually several LUNs being accessed through a single port.  This is because gigabit speed SAN connections have more bandwidth than can be utilized.  So a switch can carry multiple host/LUN connections, called oversubscribing.  The amount depends on the app and IO capability of the controller.
 
You can oversubscribe too much and slow down a highly transactional db.  In this case a dedicated link or less oversubscribing may be the key.  There is no set rule or guideline for this.  Always also consider your backup traffic, multipathing plans, zoning, and VSAN/VLANs.  

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