Veritas-bu

[Veritas-bu] Re: Implications of turning off s/w compresion?

2002-04-04 11:46:59
Subject: [Veritas-bu] Re: Implications of turning off s/w compresion?
From: kk_downings AT yahoo DOT com (kk downing)
Date: Thu, 4 Apr 2002 08:46:59 -0800 (PST)
If I remember correctly from this list there are only
two companies that actually make DLT types and there
was a way to see which vendor it was by looking at the
tape itself. Does anyone remember what this
disctinction was? As far as the color coding of DLT
tapes goes for DLT IV is there a difference between
brown, tan and black?


--- Darren Dunham <ddunham AT taos DOT com> wrote:
> > So basicaly a DLT tape is a DLT tape it's not like
> > DDS2/DDS3 incompatibilites as far as off the shelf
> > goes. In other words the Density
> specification(7000 or
> > 8000) is chosen when the tapes is mounted and has
> data
> > writen to it in a specific drive(7000 or 8000).
> This
> > is where the calibration track comes in I guess?
> Is
> > this corect? Also does DLT1 equate to the 7000 and
> > DLT2 equate to the 8000? Thanks
> 
> Actually there are several different cartrige
> formats, but you don't see
> many of the old ones around.  They used to be called
> CompactTape
> followed by a roman numeral (and maybe some other
> bits), but now they
> are called DLTtape.
> 
> The 7k and the 8k both use the DLTtapeIV for highest
> density and speed..
> That gives 35G native on the 7k and 40G native on
> the 8k.  The 7k has
> the option of using older media at the lower
> capacity and speed.  The
> IIIxt will give 15G native and the III will allow
> for up to 10G.  The IV
> came out years ago and is just about the only thing
> I've seen in the
> past 4 years.  The tapes are color coded, too.  All
> the IV tapes are a
> deep brown.  Others are black and tan, and cleaning
> tapes are white.
> 
> I don't know much about the DDS2/DDS3, so I can't
> say that they're
> different or not.  As mentioned, the density format
> of a tape is set by
> the a write starting at BOT.  You can override it
> later, but all blocks
> currently on the tape must be at the same density.
> 
> Compression can be changed during the tape write
> (possibly only at file
> boundaries though).  It is not set permanently by
> the BOT write.
> 
> DLT1 and DLT2 (and so on) in NetBackup do not
> correspond to any
> particular device or tape type.  Since the OS is
> managing the
> differences, NB doesn't need to know.
> 
> Instead, they are just there to mark certain volumes
> incompatible with
> certain drives.  It's up to you to put them into the
> categories you
> want.  If done properly, it lets you avoid trying to
> load a DLT8k
> formatted tape into a DLT7k drive (where it will
> probably generate an
> error).
> 
> The technical manuals are still online at quatum.com
> in PDF format for
> more specifications.
> 
> 
> -- 
> Darren Dunham                                       
>    ddunham AT taos DOT com
> Unix System Administrator                    Taos -
> The SysAdmin Company
> Got some Dr Pepper?                           San
> Francisco, CA bay area
>           < How are you gentlemen!! Take off every
> '.SIG'!! >
> _______________________________________________
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>
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