Networker

Re: [Networker] NW Volume Recycling Question

2007-11-26 18:08:47
Subject: Re: [Networker] NW Volume Recycling Question
From: Preston de Guise <enterprise.backup AT GMAIL DOT COM>
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Date: Tue, 27 Nov 2007 10:05:09 +1100
On 27/11/07 9:56 AM, "ct2msb" <networker-forum AT BACKUPCENTRAL DOT COM> wrote:

> The volumes in question are part of a daily pool and they just have
> incremental backups on them. Plain old incr incrementals, no numbers. So there
> shouldn't be any dependency, if I understand your answer.
> 
> Is there anything else that could be keeping all of the savesets from being
> recyclable and thus keeping the volume from being recyclable?
> 

That's not entirely correct. Incremental backups do experience dependencies.
An incremental done on night X will depend on the incremental done on night
X-1, etc.

I.e., if you have a week's worth of backups, with one full and 6
incrementals, the dependency chain (reading "a <- b" as "b depends on a")
would read:

full <- incr <- incr <- incr <- incr <- incr <- incr

I.e.:

- The first incremental after the full depends on the full.
- The second incremental depends on the first incremental, and thus in turn
also depends on the full.
- The third incremental depends on the second incremental, and thus in turn
depends on the first incremental, and thus in turn depends on the full.

Remember that dependencies are for total filesystem restoration, and thus
dependencies will exist on a tape which only has incrementals.

Cheers,

Preston.

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