Subject: Re: HD as backup (Re: RAID In general)
To: NetBSD-current Discussion List <>
From: Chuck Yerkes <>
List: current-users
Date: 04/17/2003 21:40:26
Quoting Greg A. Woods (
> [ On Thursday, April 17, 2003 at 14:41:52 (-0400), Chuck Yerkes wrote: ]
> > Subject: HD as backup (Re: RAID In general)
> >
> > Number of copies?  1.
> Don't forget that off-site archives can usually be recycled too,
> especially with very-high-capacity media where you can keep all old data
> on the same backup set.

> The speed of the hard drive as backup media, as Greywolf said, is still
> one of the key features of using low-cost hard drives though.

Not really.  I've LONG (like since 94) dumped to a spool drive
then to tape.  I've setup excessively high performance RAID boxes
to catch database dumps to keep downtime to a minimum.

This is not new.  What it new is not then cpying it to an
archive qualitity medium.

> Having very high-speed high-volume backup media radically changes the
> way one thinks about backups.  Think of the "snapshot" feature on NetAPP
> file servers, among other things.
And I backup netapps to tape.  Why?  I've had racks go bad, I've had
heads go but mostly, I've had employees come and ask for the home directory
of a developer who had left a year ago.  snapshots don't last THAT long.

> Of course if I were doing serious backups with tapes I'd definitely want
> at least two copies of each too....  (or use RAIT with striped parity)
Not done this in 20 years of mounting tapes and running backups.

> The narrower the tape the less reliable the tape and drive too, at least in my experience.

Home is DDS.  Work is AIT or DLT. Purely economics and that I owned a
DDS-2 tape changer :)

> > I have a DAT that I mail to a pal cross country every couple months.
> I suspect the likelihood of physically damaging a DAT tape and a
> properly packed hard drive when sending each through the postal mail is
> about equal these days.

The is both facetious and wrong.  And you know it.
DAT/8mm can take physical shock.  Drop a DAT (in the pretty plastic
case where they ALL live when not in a tape drive) from 20 feet.
Onto concrete.  Bet it works.  Shuffle your feet on a rug and pick
it up.  Bet it works.

Hell, I've taken 3/4" UMatic video that were dropped in WATER and
recovered them.

> > I have a box of tapes (8mm, QIC150, DAT from DDS-1 to DDS4) sitting
> > in a box in a closet.  They all still work (I question the 9-track's
> > life after 18 years since backup).
> How do you know they all still "work"?  What's your definition of
> "work"?  Can you still read exactly the same data, and all of the data,
> from them that you recorded on them originally?  How often do you check
> them?  How many tests can they survive before the tests alone cause them
> to fail?

Um, the big one is that I sucked a bunch of them off to a large drive to
try to agreggate these various things I have.  QIC 60s from 1991 worked
fine.  8mm from 92 worked just fine.  No errors and, since I was often
archiving off tar.Z files off to tape (no hardware compression then),
if tar xzf   doesn't given an error on the restored data, I have confidence.

> > I also have a 20MB MFM (or RLL) drive that's got some stuff I might
> > want.  Could you run over and get that data off please?
> We're not talking about ancient technology near-antique 20MB MFM drives
> here.

12 years is "near antique."  Then my argument stands.  

I've pulled stuff from 9track tapes in the last 2 years.

> Obviously you've kept working tape drives that can still read all your
> old media, so why didn't you keep a working system with an ST-506 and/or
> EIDE interface for your old hard drives?
8mm drive in a box.  QIC150 in a box.  Don't ahve a full PC to read the
MFM.  Sorry, that means an OS and a card and a rest of 8MHz machine.
(tho I do have a working Kaypro Model ][ and a couple apple ][s).

> > - HD's are delicate.
> Not in a properly padded box they're not....
Yes they are.  They are just in a box that reduces that.
That doesn't make them less delicate.  It attempts to deal with
their delicateness.

We can look at shock specs for DAT/8mm/DLT/AIT cases and the well
published shock specs for a barracuda.  Drives can take far far
less impact, they can take less environmental abuse, they are not
intended or packages for archival use, etc.  YOu can play semantic
games all you want, you can spent all your savings working around
this limitations (and yes, I can get an lovely anvil case that's
anti-static and padded for my drives - I used to carry around 14
expensive microphones in difficult physical situations.  It doesn't
change things.  In 10 years, your drive will likely require a whole
computer system from NOW to be read.  In 10 years, I will need a
SCSI card to use my tape drives that are already 10 years old.

(I won't archive CD - a small scratch and your done.  I might trust
a DVD or CD locked into a cartridge to last.

I'm with you, I wish that they'd keep up with storage needs.  My
mom can buy a 200GB machine for < $500 and cannot back it up
practically.  My brother in law asked about pulling a tape drive
they had in their old computer.  I mentioed it could back up around
40MB.  He just sighed.  That's a problem and a threat to the computer