building a RAID system - yup - superglue

Jeff Layton jeffrey.b.layton at
Thu Oct 9 10:35:16 EDT 2003

Robert G. Brown wrote:

> On Thu, 9 Oct 2003, Alvin Oga wrote:
> > > Pants AND suspenders.  Superglue around the waistband, actually.  Who
> > > wants to be caught with their pants down in this way?
> >
> > always got bit by tapes... somebody didnt change the tape on the 13th
> > a couple months ago ... and critical data is now found to be missing
> >       - people do forget to change tapes ... or clean heads...
> >       ( thats the part i dont like about tapes .. and is the most
> >       ( common failure mode for tapes ... easily/trivially avoided by
> >       ( disks-to-disk backups
> >
> >       - people get sick .. people go on vacations .. people forget
> >
> >
> > - no (similar) problems since doing disk-to-disk backups
> >       - and i usually have 3-6 months of full backups floating around
> >       in compressed form
> All agreed.  And tapes aren't that permanent a medium either -- they
> deteriorate on a timescale of years to decades, with data bleeding
> through the film, dropped bits due to cosmic ray strikes,
> depolymerization of the underlying tape itself.  Even before the tape
> itself is unreadable, you are absolutely certain to be unable to find a
> working drive to read it with.  I have a small pile of obsolete tapes in
> my office -- tapes made with drives that no longer "exist", and that is
> after dumping the most egregiously useless of them.
> Still, I'd argue that the best system for many environments is to use
> all three: RAID, real backup to (separate) disk, possibly a RAID as
> well, and tape for offsite and archival purposes. 

I can say with some authority that this is what we at Lockheed
Aeronautics do. And rather than extend this email by quoting
Bob below, we also have an HSM system that we use for data
we may need in the next couple of years.


Dr. Jeff Layton
Chart Monkey - Aerodynamics and CFD
Lockheed-Martin Aeronautical Company - Marietta

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