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Date:      Tue, 27 Nov 2001 02:35:42 -0800
From:      "Ted Mittelstaedt" <tedm@toybox.placo.com>
To:        "Anthony Atkielski" <anthony@freebie.atkielski.com>
Cc:        <freebsd-questions@FreeBSD.ORG>
Subject:   RE: SCSI tape back that works under FreeBSD
Message-ID:  <000001c1772f$43dcda00$1401a8c0@tedm.placo.com>
In-Reply-To: <001b01c17724$3c3b6ce0$0a00000a@atkielski.com>

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>-----Original Message-----
>From: Anthony Atkielski [mailto:anthony@freebie.atkielski.com]
>Sent: Tuesday, November 27, 2001 1:17 AM
>To: Ted Mittelstaedt
>Cc: freebsd-questions@FreeBSD.ORG
>Subject: Re: SCSI tape back that works under FreeBSD
>
>
>Ted writes:
>
>> I mainly wanted to emphasize that while DAT is
>> fine for light use, it won't stand up to a tape
>> cassette's worth of data totally rewritten every
>> night for a year.  You have to be a little careful
>> when recommending solutions to note the environment
>> they work in.
>
>I think my suggestions match the most likely FreeBSD production environments.
>Additionally, I'm not convinced that DATs are as fragile as you imply.
>

you really have to put the described environment in before making these
sorts of statements.

All tape drives are mechanical systems and all mechanical systems are subject
to
wear.  They all have a finite lifetime.  In short, they are DESIGNED to wear.

You call a tape drive wearing out fragile?!?!  This is normal!  It's only
abnormal if the drive wears faster than designed.

  Anyone running tape drives, or
printers, or any kind of other mechanical device regularly in a higher
capacity
production environment must plan the lifespan and replacement cycle of the
system and is going to be aware of their production environments wear demands.

>> It depends on the drive - on the Exabyte 8mm
>> drives it certainly was.  On the others, not so much.
>
>I've had lots of trouble with 8mm drives, but none with 4mm (DAT)
>drives.  Are
>you sure you've had problems with the latter, or are you just grouping both
>types of drives together?

I've had problems with both.  In fact, I've not seen any other 8mm drives
than Exabyte, or OEM'd Exabyte.  Many of the DAT drives I've dealt with have
been the 4mm jobs.

  As I recall, 4mm drives have a much
>better reputation
>for reliability than 8mm drives, and my own experience on both types
>of drive is
>congruent with that reputation.
>

4mm drives originally wern't used as often in high-production environments
than
8mm because they held less data, because the 8mm drives had been around
longer, and because originally they were more cheaply made.

>> It would suck mightily if you had 3 years of
>> backup tape saved up, all hardware compressed, and
>> you replaced the tape drive and found all old tapes
>> to be unreadable.
>
>I've never heard of anyone restoring three years of backups.  In
>fact, I'd guess
>that about 95% of all file restorations are from the most recent backup, and
>virtually nothing ever needs to go back more than two or three days.
> Anything
>three years old is an archive, not a backup.
>

And if you have never had to go back and find ONE file from 3 years ago (or
longer)
then I doubt you will have worked in the kind of higher-capacity production
environments that I'm talking about.


Ted Mittelstaedt                                       tedm@toybox.placo.com
Author of:                           The FreeBSD Corporate Networker's Guide
Book website:                          http://www.freebsd-corp-net-guide.com



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