[BBLISA] Definition of dump levels?

[Scott Ehrlich]

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: bblisa-bounces at bblisa.org [mailto:bblisa-bounces at bblisa.org] On
>> Behalf Of Scott Ehrlich
>> Sent: Saturday, January 05, 2008 8:33 AM
>> To: bblisa at bblisa.org
>> 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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