ADSM-L

Re: LTO3 tapes problem !

2005-09-07 11:16:09
Subject: Re: LTO3 tapes problem !
From: Richard Sims <rbs AT BU DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 7 Sep 2005 11:14:53 -0400
On Sep 7, 2005, at 8:06 AM, Goran wrote:

...i'm confused since tsm53 admin guide says :
"
The LTO Ultrium Generation 1 drive cannot support LTO Ultrium
Generation 2
media. For this reason, you cannot mix Ultrium Generation 1 and
Ultrium
Generation 2 media in a storage pool that shares both Ultrium
Generation 1
and Ultrium Generation 2 drives. ...

The statement is less confusing upon review of the technology "rules"
defined at www.lto.org, and specifically in this case on page
  http://www.lto.org/newsite/html/about_faqs.html
which says:
"1) An Ultrium drive is expected to read data from a cartridge in its
own
    generation and at least the two prior generations.
 2) An Ultrium drive is expected to write data to a cartridge in its
own
    generation and to a cartridge from the immediate prior
generation in
    the prior generation format."

The key is the format: there has to be a common-denominator format for
the mixed drives to be able to fully read and write all the tapes, and
that format is the least format used by any of the drives.  But if a
superior format tape is present, that tape cannot be appended to
by a lesser (earlier generation) drive.  This is just basic technology
stuff: a drive can't do more than it was designed to.  Later designs
have more advanced capabilities (density, number of tracks, etc.).
To successfully implement a mix, there needs to be full compatibility.

   Richard Sims