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March 2001, Week 2

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Subject:
Re: Magnetic media shelf life
From:
Denys Beauchemin <[log in to unmask]>
Reply To:
[log in to unmask][log in to unmask]]
> Sent: Saturday, March 10, 2001 12:02 PM
> To: [log in to unmask]
> Subject: Re: tail -f STDLIST
>
>
> John Dass wrote:
> > I remember that in Unix you can tail -f the stdout of a running
> > program so as to monitor the execution. However in MPe you have
> > [...]48_12Mar200107:17:[log in to unmask]
Date:
Sun, 11 Mar 2001 19:47:43 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (52 lines) 
It all depends on many variables.  Tapes require proper storage to maintain
long shelf life.  A magnetic tape can last many years, but the problems could
be in finding the appropriate device and even software to read the tape.

As for CDs and DVDs, the issue is much more complex.  Whilst CDs and DVDs are
not magnetic, they are optical and subject to scratches and blemishes.

Regular CDs are pressed, not written.  The information is kept in tracks,
starting from the center of the disk, working outwards in a long spiral.  If
you scratch the bottom of the CD, you can usually polish that up with
toothpaste (not gel) or you can get a polishing kit for the disk. If you
scratch the top, you will alter the reflectance of the CD to the laser and you
will lose the data.  I believe painting the scratch can restore a CD, but I
have never tried it.

As for the recordable CDs, there are two kinds, the one that you write only
once (CD-R) and the re-writable (CD-RW) kind.  For purposes of long term
retention, stay away from the CD-RW.  They will change state (because they can)
and lose the data over time.  As for the CD-R, use top quality or archival
quality blanks and your data should last many years or decades.  Use an
inferior brand and risk losing your data over time.  Protect your CDs from
scratches, on both sides.

The same issues affect DVD, although there are currently very few writable or
re-writable DVD drives around.

Kind regards,

Denys. . .

Denys Beauchemin
HICOMP
(800) 323-8863  (281) 288-7438         Fax: (281) 355-6879
denys at hicomp.com                             www.hicomp.com


-----Original Message-----
From:   Brad Feazell [SMTP:[log in to unmask]]
Sent:   Friday, March 09, 2001 11:32 AM
To:     [log in to unmask]
Subject:        Magnetic media shelf life

Does anyone have a good fix on the shelf life of various backup media? I've
got old reel tapes and DAT tapes stored offsite that range from one to ten
years old. Even if I had a reel tape drive anymore, I question whether those
ten year old tapes are still readable.

What about CDs and DVDs? I read an article today that suggested that DVDs
are good for over 100 years. Are CDs and DVDs totally non-magnetic?

Brad Feazell

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