Veritas-bu

[Veritas-bu] VTL questions

2005-11-21 13:42:26
Subject: [Veritas-bu] VTL questions
From: pkeating AT bank-banque-canada DOT ca (Paul Keating)
Date: Mon, 21 Nov 2005 13:42:26 -0500
How apropos.....

I read this message this morning, about an hour before going to a
Falconstore presentation

I just got back from the presentation ...... not by an OEM, but one of
the engineers from Falconstore)

Here's the skinny....

In one configuration, you can connect the VTL to the media server, and
the physical library to the VTL.
You tell the VTL to inventory the library....the VTL gets its barcodes
from the library.
The VTL looks like the library to the backup server.......you tell the
VTL what type of tape drive to mimic, and what compression ratio to
assume.
Your backup runs to the VTL untill the virtual tape is full, then your
tape gets duped to the physical tape in the library with the same
barcode.
You have to assume a conservative compression ratio, because if you
assume to much compression, and the image doesn't fit on the tap,  the
dupe fails, and to quote the engineer. "you're screwed".

In the other configuration, you configure the VTL as a standalone
library, can be any type of library....your physical library my be a STK
L700, and you may present the NB server with a STK Powderhorn.......you
specify a barcode range for your VTL, different than the barcode range
of your physical tapes, and you can use the physical library and the
virtual library separately as separate storage units, backing up to both
(some jobs to VTL, some to phys tape) during your regular backup window,
then during regular business hours, use NB Vault to dupe your VTL tapes
to phys tape.....in this case, there isn't a one-to-one pairing between
virtual tapes and physical tapes, so you can vault 3 virtual tapes onto
2 physical tapes, if that's the way your compression works out.

You can also make the VTL into one stu, and the phys lib into a second
STU, and put them in a stu group......so jobs can go to whichever is
available, then cross vault from one to the other and have your data on
both.....


In the first case where the VTL is acting as a cache for your phys lib,
and the barcodes are the same, the VTL manages everything.
If your image is still on disk, the restore comes from the disk.....if
the image has expired from disk and is only on tape, it will come
directly from the tape, proxied by the VTL.....no need to import. From
NB's perspective, you'll get the media request in the same way....put
the tape back in the phys lib, and the VTL will proxy it to the NB
server transparently.....NB never knows the difference.

If your data is on Disk, and hasn't been moved to tape yet, and you try
to export the tape via your mailslot/CAP, etc, there will be a delay
while the data gets copied to tape, then it will show up in the CAP.

Any questions? Let me know.

Paul

> -----Original Message-----
> From: veritas-bu-admin AT mailman.eng.auburn DOT edu 
> [mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of 
> Lee, Kenneth (SBS US)
> Sent: November 18, 2005 8:32 PM
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] VTL questions
> 
> 
> We are looking into VTL and I am getting conflicting stories.  Here is
> what I want to do and I would like to know if it is possible.
> 
> I have a STK SL8500 physical tape library.  NetBackup 5.1 
> Solaris Master
> server & media servers.
> 
> 
> I would like the following:
> 
> 1.    Backup some clients to VTL.
> 2.    At the same time, backup some clients to STK SL8500.
> 3.    In the day time, I would like the VTL to migrate the virtual
> tapes to the STK SL8500 physical tape.  I don't want to do duplication
> through NetBackup.  Since the VTL tapes have the same bar code as a
> physical tapes, NetBackup will think that the tapes are ejected.
> 
> Questions:
> 
> If I attached the physical tape library to a VTL, can I still use the
> same tape library for NetBackup?  One vendor said yes, 
> another said no.
> They both use FalconStor solution.
> 
> If I used the VTL to move the virtual tape to a physical 
> type, during a
> restore, will I need to bring the virtual tape back to the 
> VTL before I
> can restore?  My question is why can I not just put it into 
> the physical
> tape library as they have the same bar code?  I don't want to do any
> importing either.  Am I missing something?
> 
> Thanks,
> Ken
> 
> 
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