Legacy HDS Forums

How many controller ports per LUN?

Discussion created by Legacy HDS Forums on Aug 20, 2007
Latest reply on Aug 22, 2007 by Legacy HDS Forums

Originally posted by: TTF



Here's the scenario:
A single Unix host with 2 HBA cards (each with a single FC port).
2 Fibre switches (not connected) i.e. 2 Fabrics
One AMS1000 array with 0A 0C 1D & 1B on fabric 1 and 0B 0D 1A & 1C on fabric 2.

Over the coming months, the Unix host will be assigned numerous LUNs with varying levels of I/O.
For each LUN configured, what is the best practice for the number of controller ports to use?
(Obviously I intend to use multi-pathing software on the host.)

My experience is with EMC hardware where on a given array all ports are pooled for all hosts. So for an array with 8 ports, 4 will be used by the controller that owns the LUN and the other 4 will be there in standby should the first controller fail. So I'd see balanced I/O across the 4 active ports and no I/O across the 4 standby ports.

I have seen HDS arrays configured with just 2 ports (one on each controller) for each LUN and an attempt made to manually balance I/O across all the ports for all the LUNs.

In a scenario where it is nigh on impossible to balance the I/O manually across the 8 ports, surely it is better to pool the resources or is there a good reason not to do this?

Regards
TTF

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