🚀 go-pugleaf

In article <4f6oej$mp9@steel.interlog.com> ldh@interlog.com (Laurent-Daid Hasson) writes:
>
>I have seen ONE product called TapeDisk that claims that it can make accessing a 
>SCSI tape drive as if it were a regular HD (besides performance of course). 
>
>Where is the catch? Am i missing something? Or is it simply one of these things 
>that everyone knows about, but which is unknown to lowly indows users?
>

The catch is that you have to write a filesystem driver for the tape device. 
This is not a trivial task.

In article <4f6oej$mp9@steel.interlog.com> ldh@interlog.com (Laurent-Daid Hasson) writes:

>I have seen ONE product called TapeDisk that claims that it can make accessing a 
>SCSI tape drive as if it were a regular HD (besides performance of course). I 
>uess that what it does is to install a new file system and mounts the tape drive 
>as a drive letter. 

I use TapeDisk (or, as the authors quaintly call it, TAPEDISK).  It does 
indeed mount a tape drive as a DOS/Windows drive letter.

More specifically, it creates "chapters" on a tape and it can mount one of 
these chapters as a drive letter.  What is really powerful is what happens 
when you mount an existing chapter and start writing more files to it.  You 
can't rewrite the tape in place, so TapeDisk creates a *new* chapter at the 
end of the tape.  It writes only your changes to this chapter, but it writes a 
full file directory including both the data stored in the new chapter and the 
data in the original chapter.

From your point of view, the original chapter and the new one look like 
complete copies of your data, even though the new chapter really contains only 
the incremental changes.

TapeDisk includes some utilities that take advantage of this chaptering to do 
incremental backups.  This is completely different from the grossly inadequate 
way traditional backup programs do incremental backups.

With a traditional backup program, when you do an incremental backup, the 
program looks *on the disk* to see which files have not yet been backed up.  
Fine, but it only lets you do *one* incremental backup.

Suppose you have made two full backups, and now you would like to bring both 
these tapes up to date.  You can't do that with traditional incremental 
backups: you can only bring one tape up to date.  If you want to have two 
tapes that both contain complete backups, at least of them has to be a full 
backup, not an incremental.

With TapeDisk's chapter approach, an incremental backup backs up files that 
are not already on *that* particular tape.  So you can take two tapes, run 
"incremental" backups on both, and now each one is really in effect a full 
backup.

The only other backup program I know of that does this is Retrospect on the 
Macintosh.  It's really a puzzle that all the PC backup programs use the 
inherently flawed method of checking disk attribute flags.

-Mike (Mike@Geary.com, http://www.geary.com)

In article <4f6oej$mp9@steel.interlog.com>, Laurent-Daid Hasson
<ldh@interlog.com> writes

>Where is the catch?

Speed ?

-- 
John Beardmore

In article <Mike.1326.005373B4@Geary.com> Mike@Geary.com (Michael Geary) writes:

>I use TapeDisk (or, as the authors quaintly call it, TAPEDISK).  It does 
>indeed mount a tape drive as a DOS/Windows drive letter.

What a stupid thing to say. The authors of a product have every right to name 
it whatever they want. I should have written:

>I use TAPEDISK (or, as this writer quaintly calls it, TapeDisk).  It does 
>indeed mount a tape drive as a DOS/Windows drive letter.

<g>

-Mike (Mike@Geary.com, http://www.geary.com)

Schwann (schwann@aztec.co.za) wrote:
> my DAT tapes say  DC2120....

Time for a little background regarding tape backup systems ...

A DC2120 tape is a QIC40/80 tape, not DAT.  It's the type used in Colorado
Jumbo drives and their ilk (QIC = quarter-inch cartridge).  DAT, on the
other hand, is 4mm; these tapes will be labeled as 60, 90, or 120 meters. 
QIC tapes have a heavy metal base and are built quite sturdily.  4mm tapes
have thin plastic housings.

DAT always implies SCSI, but SCSI does necessarily imply DAT.  Many SCSI
tape drives are DAT, but many others are QIC, and some are neither (8mm
for instance).

Strictly speaking, true DAT tapes are not certified for use in computers,
but rather for audio equipment.  The more proper term for the computer
variety is DDS; DAT is a common, albeit inaccurate term for 4mm tapes used
in computers.

Ken

-----------------------------------------------------------------
Ken Holt    Pittsburgh, PA      email: kholt@telerama.LM.com
                                www  : http://www.LM.com/~kholt
-----------------------------------------------------------------
-- 
-----------------------------------------------------------------
Ken Holt    Pittsburgh, PA      email: kholt@telerama.LM.com
                                www  : http://www.LM.com/~kholt
-----------------------------------------------------------------

Much obliged for the lesson...

Yes, the QIC tape is a cool metal based operation:)

best,

schwann


ps...but how do i backup under windoze95?

kholt@telerama.lm.com (Ken Holt) gab die nachfolgende Information
kund:

>Strictly speaking, true DAT tapes are not certified for use in computers,
>but rather for audio equipment.  The more proper term for the computer
>variety is DDS; DAT is a common, albeit inaccurate term for 4mm tapes used
>in computers.
Does this mean, that audio-DAT and the DAT-streamers have nothing in
common? What I'm exspecially interested in: I thought about a
possibility to copy DAT audio tapes with my streamer and to copy a
wave file (or something like that) with my DAT streamer to a DAT audio
tape. Is there a chance to do things like that?

Thorsten

--------------------------------------------------------
Thorsten Kuthe, Melatenguertel 23, 50933 Koeln, FRG       
E-mail: a2753200@athena.rrz.uni-koeln.de
      ***** Never change a working computer *****

a2753200@athena.rrz.uni-koeln.de (Thorsten Kuthe) wrote:

>Does this mean, that audio-DAT and the DAT-streamers have nothing in
>common? What I'm exspecially interested in: I thought about a
>possibility to copy DAT audio tapes with my streamer and to copy a
>wave file (or something like that) with my DAT streamer to a DAT audio
>tape. Is there a chance to do things like that?


I far as I've heard, only a certain SUN DAT would be able to play a music
DAT tape.  Potentially, you can get TAPEDISK, a USD$200 util to make your
DAT looks like a HD, and use your normal wave tools to record stuffs
there.  The format, however, would in be tapedisk's proprietary and would
not play in a music DAT, but only through the computer.



-billc