On Sun, 6 Jan 2008, Edward Ned Harvey wrote:
A dump of any dump-level will backup all files that have changed since the
most recent dump of a lower dump-level. This is basically an unnecessarily
large level of abstraction, the guys who originally wrote it were thinking
*way* broader than necessary.
There's a nice simple analogy, if you're familiar with Full / Incremental /
Differential backups.
* Think of a Full Backup like level 0. It gets everything no matter what.
* Think of a Incremental like level 5. It gets everything that changed
since the last full, and creates an intermediate stage, so your
differentials/level 9's don't have to copy that stuff again.
* Think of a Differential like level 9. It gets everything since the most
recent 0 or 5.
Depending on how much data you're talking about, you might do something like
this:
Run a daily script, which does this:
If today's the 1st of the month,
Do a level 0.
Else:
If today's Sunday,
Do a level 5
Else:
Do a level 9
That would get you your Monthly fulls, Weekly incrementals, and daily
differentials.
As mentioned by John, most people don't have a large enough quantity of data
to mess around with Incremental/level 5. Most people will do something like
weekly level0, and daily level9.
Now, I have a 12-tape changer (Overland):
- Do I use tape 1 for all backups?
- If yes, I perform a level 0 on it. I then perform a subsequent
(/dev/nst0) level 9 to it. Will dump complain that a level 1
doesn't exist and force a level 0 again?
Else
- Do I use tape 1 for level 0
- If yes, that remains my level 0, and I use tape 2 for level 9.
- Now, will dump say tape 2 (brand new) has no previous data on it
and force a level 0 before going further?
I'm trying to collect as much good, nonconflicting answers as possible
over the weekend heading into the workweek, and I don't have such a tape
drive at home, nor can I bring it home, and I've received conflicting
responses from other lists, so it will be interesting how things
ultimately work themselves out through my own testing and actual results.
I will say this list _has_ been wonderful for accurate responses.
Thanks again.
Scott
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Scott Ehrlich
Sent: Saturday, January 05, 2008 8:33 AM
To: [email protected]
Subject: [BBLISA] Definition of dump levels?
I've seen so many references to dump levels, but none of them,
including the
man page, actually says what, specifically, each level covers.
For example, a level 0 would presumably back up everything. But will
it still
do so if I perform a level 0 today, update /etc/dumpdates, then perform
another
level 0 just after, and no files have changed?
What about the other levels? What do they do?
Thanks.
Scott
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