Networker

Re: [Networker] Confusion over incremental and levels - 3 IMPORTANT questions!

2004-01-23 11:55:02
Subject: Re: [Networker] Confusion over incremental and levels - 3 IMPORTANT questions!
From: Dave Mussulman <mussulma AT CS.UIUC DOT EDU>
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Date: Fri, 23 Jan 2004 10:54:54 -0600
On Fri, Jan 23, 2004 at 11:28:29AM -0500, George Sinclair wrote:
> Mon=full, Tue=incr, Wed=incr, Thu=incr, Fri=level5, Sat=incr.
>
> 1. Does the Sat incr capture all changed files since Fri, or does it
> instead capture all changed files since Thu?
>
> I was kinda stumped on this question, but I thought it would capture all
> changes since Fri.

The Unix nwadmin GUI Indexes menu shows the dependencies in a tree-form
which makes things a little simpler.  Saturday's incremental grabs all
the changes since Friday.  Doing a restore from Thursday may require
tapes from Monday, Tues, Wed, and Thurs.  Doing a restore from Saturday,
might require Monday, Friday, and Saturday.


> 2. We typically run descending levels throughout the month with
> incrmentals and then a full at the end of the month. I was operating
> under the assumption that if someone needed to rebuild something, at
> worst case, they would need the last full tape(s), the most recent level
> backup tape(s), and then all incremental tape(s) after that. In other
> words, if you were performing a saveset recover (so you're doing this
> manually) of an entire file system as it most recently existed, then you
> would select the most recent full instance, the most recent level
> instance and all incrmentals after that, yes?

Sounds right to me, although I don't know if I've ever done that saveset
recover progression.  It sounds like what the recover program is doing
in that situation, though...


> 3. Also, what would happen in the following scenario:
>
> Mon=full, Tue=incr, Wed=incr, Thu=level5, Fri=incr, Sat=incr, Sun=level5
>
> Will Sunday's level 5 capture all changes since Thursday's level 5 or
> will it, too, go all the way back to Monday just like the first level 5
> did?

Doing a later backup of the same level as a previous one will 'absorb'
the previous level.  To slightly change your example,

Mon=Full, Tues=inc, Wed=inc, Thu=level5, Fri=inc, Sat=level5, Sun=inc

To do a restore from Sunday, you would only need Monday, Saturday, and
Sunday.  Our real-world example: we do incrementals on the weekday,
level5 backups on the weekends, level 3s monthly, fulls quarterly.
Worst case scenario for a restore (needing a full restore on the last
day of the quarter before the next full,) would require the fulls, the
last level 3, the last level 5, and the incrementals since the last
level 5.

Does that make things cleaer?

Dave

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