[vox-tech] [fwd] backup solutions for 3 people

[Karsten M. Self]

on Wed, Jun 29, 2005 at 08:35:21AM -0700, Jonathan Stickel (jjstickel at sbcglobal.net) wrote:
> Karsten M. Self wrote:
> >
> >Tape.
> >
> 
> I've never really used tape drives, but my one experience was not good. 

One experience vs. standard procedures are radically different
datapoints.

> Someone else backed up data to a tape on a mid 90s unix machine, I
> think.  I needed the data about a year ago.  We were unable to access
> the data because we were clueless about how the tape was formatted,
> what software utility wrote to the tape, etc.  The computer that wrote
> to the tape was long gone.

As others have suggested, almost certainly tar.

A *good* tape back up policy involves labeling the tape to indicate just
this.

Note that there are systems which use other utilities to create backups,
notably in the legacy MS Windows world (for which there is no one
ubiquitous standard like tar), in which case, reading the tape does
become something of an exercise in creative forensics.

Even with tar, there can be some curves, most notably blocking factors.
Most admins will just use system defaults, but it's possible to state
alternatives, nominally for storage efficiency.  This is a standard
practice in the mainframe world, less so with 'Nix.

That said, tar to tape is reliable, bog standard, and recoverable on
virtually any 'Nix system in existance.  While other backup systems
offer some convenience factors, etc., the ability to do bare-iron
restores without having to install some complex and/or arbitrary package
is very, very useful.

 
> From this experience, it seemed that there is no standard when it
> comes to tape formatting, reading, and writing.  Has this changed?  If
> not, they don't seem that useful to me.

Did you ever try contacting the person who'd created the tape to ask how
they'd made it?

I've dealt with many, many, many tape dumps in my life as a data
analyst.  Knowing how a tape was created, where, with what, how much
data is on it, and the data format, are very useful information.

Suggested labeling:

  - Tape, date, description, creation command (including blocking factor
    if any), creator's name.  This should fit on a standard lable.
    Bonus points if your labels are created automatically and printed as
    part of the backup.

  - Anciallary docs should describe the file(s) (or directory trees),
    total data stored, and a checksum (md5sum) if possible, particularly
    for long-term archival data.

If you're running your own standard backup system, odds are that most of
this is either known or implied, but doesn't hurt to document it
someplace.


Peace.

-- 
Karsten M. Self <kmself at ix.netcom.com>        http://kmself.home.netcom.com/
 What Part of "Gestalt" don't you understand?
    This suggests a more troubled future for Gnome than I had imagined.
    - Chip Salzenberg, on GNOME developer attitudes
      http://zgp.org/pipermail/linux-elitists/2004-January/008588.html
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