Something additional on the topic:
According to IBM 3583 Guide you can configure it for dual-path. It is not
full dual-ported as 3590 drives but still gives some additional
protection. The configuration in the guide is utilizing twin-tail SCSI:
FC port from the SAN switch
---> SAN Data Gateway module in first (!) 3583
---> LVD SCSI Ultrium drive (3583 does not have FC drives) in first 3583
---> LVD SCSI Ultrium drive (3583 does not have FC drives) in first 3583
---> LVD SCSI Ultrium drive in second 3583
---> LVD SCSI Ultrium drive in second 3583
---> SDG module in second library
---> SDG module in second library
---> port in another SAN switch
---> port in another SAN switch
While this is not full no-single-point-of-failure configuration it gives
While this is not full no-single-point-of-failure configuration it gives
some additional protection against SAN switch, FC cable or SDG module
failure. SCSI failures are not covered but would affect just part of the
library.
The new for me was that this is *supported* configuration. So I am sharing
this with you. And because module in 3583 is functionally equivalent to
stand-alone device (2108-G07) I think same should be possible for 3584
with SCSI drives and two SDGs.
Somewhat strange SCSI drives to allow little bit higher availability
compared to FC but is a fact - if the SAN switch a drive is attached to
fails drive is not accessible. In pure FC environment to implement
something like the SCSI conf we would need to over-complicate the fabric
with hubs between two switches and drive(s).
At the end this achieves only redundancy not load-balancing.
Just some thoughts.

Zlatko Krastev
IT Consultant




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Subject:        Re: Atape driver 7.0.3.0 auto failover

The 3590 is a dual ported device.  It actually has two fiber port WWPNs.
AIX actually is talking to both ports all the time but only sends out
primary IO right now to whichever is the current primary.  What is coming
is
load balancing based on what I know.  This way the ES-1000s will have
balanced IO if both ports are connected to 2 different pathways
(ES-1000s).
Finally, there is a reason 3590 is far superior.