Mr Forray,

I know a lot about this problem you are dealing with.  My name is George 
Blackwood.  I was a Systems Engineer with IBM for 30 years.  Among other 
things, I was a SAN, tape, and TSM specialist.  I have been retired for 2 
years, 1 month.  I have my own consulting business doing what I did when I was 
an IBMer.

When Linux is rebooted (RedHat, SLES, whatever), it will scan and re-discover 
its SCSI and FCP (Fibre Channel Protocol) tape resources without regard of what 
it knew about those same devices before the reboot (this is not the case with 
some UNIX systems).

So, unless you have one changer and one tape drive, you have no guarantee that 
the Linux device numbers will be the same after reboot.  So, chances are 
IBMtape0 will be IBMtape20 the next time you reboot.

IBM's answer is to set "SANDISCOVERY ON".  This works sometimes for a small 
number of drives (under 20), and will sometimes work for more.  But after 18 
months of being in and out of IBM PMRs and "CritSits", I have given up on 
sandiscovery to fix this issue.

I wrote a BASH script to fix this issue.  A current customer of mine has 8 
RedHat Linux servers sharing 12 TSM instances (we can move them around as need 
be).  Two instances are Library Managers.  All instances have access to 4 EMC 
EDLs.  Each EDL has 80 drives.  So that comes to 3890 drives paths, plus 4 
Library paths to maintain.

The script I wrote discovers what TSM instances (Library Servers and Clients) 
are running on a given Linux server that has just been rebooted.  It 
compensates for any drives that may be mounted, or any Libraries that are in 
use, and re-defines all the Library and drive paths for any TSM instance on a 
given Linux server.

So if one of the 8 servers needs to be rebooted, the script is run on that 
server after reboot.  There is no need to unmount and quiesce Libraries.  The 
only requirement is the Library Managers must be up.  The script will also find 
what drives are in a SCSI reserve "lock out".  And, it is safe to be run during 
full production time.

I can give you a few pointers to write a similar script (for free), or for a 
fee, write it for you.  I guarantee my work.

George Blackwood
Blackwood Data Protection Consulting, LLC
785-218-9961
georgeblackwood AT sunflower DOT com

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