Question on FC tape drives.

        Folks,

        We are moving from 3590E tape drives to 3592 tape drives. We are
also moving from a "direct attach to the TSM server" to a "attachment
through a FC switch".   I'm sure I'm not the first person to make this
change in their environment? Any hints anyone would like to share with
me?

        All my TSM servers are on AIX 5.2 and are using the latest and
greatest Atape drivers.

        As I read the documentation on the Atape drivers:

        
(ftp://ftp.software.ibm.com/storage/devdrvr/Doc/IBM_TotalStorage_tape_IU
G.pdf)
        
        I see that in this new configuration, I could take advantage of
the "Automatic failover" and "Dynamic load balancing" features.  As I
read through the document (Chapter 6), it looks like upon a path
failure, is supposed to fail over transparent to the user, but then has
this note that concerns me:

        2. The AIX operating system only supports a static configuration
of devices, which also applies to the Alternate Pathing and Failover
Support. When 
devices are initially configured at a specific SCSI ID and physical
connection (drive port, host bus adapter, and switch number/port, if
applicable) and in the Available state, changing the physical device
address/connection without either rebooting or unconfiguring and
reconfiguring the devices has unpredictable results and is not
supported.

        Also, it looks like when you remove your rmt devices (say, to
upgrade the Atape drivers), it looks like the RMT devices may get
reconfigured with totally different rmt numbers, requiring a reconfigure
of the devices defined to the TSM server. 

        I'm kind of an orderly guy and like to have my rmt devices
defined sequentially for ease of troubleshooting, but it sounds like it
will take some work on my end to get it to line up nicely like that.

        I will be starting my testing phase next Monday where I will
have 2 FC drives and 2 HBAs attached to the SAN. I am going to configure
the FC ports so that both HBAs see both tape drives, so I think I will
see 4 new RMT devices when I run a 'cfgmgr'. 

        Anybody else set up in this kind of environment? Any
hints/helpful commands they would like to share with me?

Thanks,
Ben Bullock
Micron Technology 
Boise, Id