Subject: Re: Tape Backups -- tar vs. dump
To: None <>
From: Aaron J. Grier <>
List: netbsd-users
Date: 01/02/2001 17:02:03
On Tue, Jan 02, 2001 at 05:47:45PM -0600, John Maier wrote:
> So...
> -1 will backup the changes from -0
> -2 will backup the changes from -1
> -3 will backup the changes from -2
> and so forth, correct?


> (The man page should be updated to elaborate on this issue)

like most things unix, the information is in there, but is very
terse.  from dump man page:

	A level number above 0, incremental backup, tells dump
	to copy all files new or modified since the last dump of
	a lower level.  The default level is 9.

> So I should define for each day it own dump level...
> i.e.
> Saturday 1:00am : dump -0 ...
> (Skip Sun and Mon, because previous day not a work day(for us :-))
> Tuesday  1:00am : -1
> Wednesday 1:00am : -2
> Thursday  1:00am : -3
> Friday  1:00am : -4
> Saturday start over with -0
> Does this look like a sane system?

it'll work, but if you need to perform a full restore from friday,
you'll need to restore five tapes.  using the tower of hanoi algorithm
as mentioned in the dump man page in the sequence 0 1 3 2 5 means you
would only have to restore four tapes.

I'd also suggest two (or more) sets of tapes with one of them stored
off-site, so in case your computer room burns up, or somebody goes crazy
with a magnet, or your level 0 tape fails, you'll still have some kind
of backup.

I use two sets of tapes.  every month I perform a level 0.  every week
goes 1 3 2 5 4.  at the end of the month this set is swapped with the
off-site tapes.

  Aaron J. Grier | "Not your ordinary poofy goof." |
   "[I]f you can find the purity in hardcore and gabber, I guess you're
    already screwed up enough."  --  Drew Smith