Veritas-bu

Re: [Veritas-bu] LTO3 and LTO2 compatibility

2007-11-02 11:34:18
Subject: Re: [Veritas-bu] LTO3 and LTO2 compatibility
From: A Darren Dunham <ddunham AT taos DOT com>
To: Veritas-bu AT mailman.eng.auburn DOT edu
Date: Fri, 2 Nov 2007 15:15:00 +0000
On Fri, Nov 02, 2007 at 08:54:32AM -0400, Jeff Lightner wrote:
> Is the LTO not like DLT where one has to specify device to use to get
> correct density (at least in UNIX environments)?

No, it's different.

> I know that in the
> past I had to find the device with correct major/minor when writing to
> an older DLT  on a newer drive in order to be sure I could read that DLT
> on the older drive.

Right.  That's because DLT support multiple formats on the same media.
LTO does not.  With DLT you can use a "high-end" tape (like a
CompactTapeIV) and place a low-density format on it to be compatible
with a lower-end drive.  That selection is done via the device file on
most Unix systems.

With LTO, that choice isn't available.  The LTO3 cartridge can't be used
in lower-end drives, so there's no need to support lower densities on
it.  When you insert an LTO2 cartridge in a drive, the density is
unique.  The only thing the device file would do is enable or disable
compression.

> That is to say does just specifying drive type in NetBackup sufficient
> or is it not important to insure the correct device file is mapped?  

Just specifying the drive type in NetBackup is irrelevant to the format
used (for any media type).  The device file is important for some media,
but not for LTO.

-- 
Darren Dunham                                           ddunham AT taos DOT com
Senior Technical Consultant         TAOS            http://www.taos.com/
Got some Dr Pepper?                           San Francisco, CA bay area
         < This line left intentionally blank to confuse you. >
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