[Veritas-bu] RE:VTL question

Hi Marco,
        Emulation is the term for what a device reports to Inquiry scsi 
commands. In your particular case, the "native emulation" (or true name) of 
your VTL is FALCON VTL. I'm assuming you have gone into the unit's 
configuration and have changed it to the STK with SDLT drives.  
        Effectively, what you have done on the unit is told it to lie when it 
is asked for its name. so, now when NBU comes and talks to it, your VTL just 
claims to be an STK with SDLT drives. 
        Emulation is used mostly to trick OS's and SW Packages into talking to 
a device that they would not normally talk to or configure. Since 90% of tape 
drives and Robots use an identical SCSI command set, this allows people to use 
unsupported devices with their OS/SW combination. In the early days of AIT tape 
drives, few Unix OS's knew how to deal with them. We would routinely have 
customers set them as Exabyte or DLT drives and this solved the configuration 
issues. 
        Since NBU cannot know that the device is really a VTL and since NBU 
supports the STK library, it will configure the device and use it as if it 
really is an STK library. This will work fine as long as NBU does not issue a 
SCSI command that is specific to the STK Library or SDLT drives that your VTL 
does not support. This is pretty unlikely, but ti does exist as a possibility. 
        There is also the problem of Support from Veritas. If you call in for 
Support, when they find out that you are not using their "approved 
configuration" and emulation settings, they will turn you away for "Unsupported 
environment, good-bye".
         
        I hope this info helps. 

Mark Pinder : 
Systems Engineer: 
Spectra Logic : 

From: "marco chiapusso" <mchiapusso AT hotmail DOT com>
To: Veritas-bu AT mailman.eng.auburn DOT edu
Date: Fri, 02 Dec 2005 09:42:00 +0100
Subject: [Veritas-bu] VTL question

Hi guys,
does anyone implemented a Virtual Tape Library?
We are testing 2 type of VTL
On the comp matrix of NBU I see that some VTL are supported with inquiry 
string... what does it means? When a VTL emulate a tape library the software 
see the emulated library.... For example the Falconstor VTL it's supported 
with "Supported with "FALCON VTL" inquiry string and only as IBM LTO drive. 
Direct backups to physical tape drives not
currently supported." It's false because if I emulate a STK SL500 with SDLT 
drive netbackup with the discovery see the STK library and SDLT drive...

Help me to understand!!!




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