Networker

[Networker] Archive bit - was Re: [Networker] Confusion over incremental and levels

2004-01-23 12:19:21
Subject: [Networker] Archive bit - was Re: [Networker] Confusion over incremental and levels
From: Duncan Greenwood <duncan.greenwood AT BTINTERNET DOT COM>
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Date: Fri, 23 Jan 2004 17:19:02 -0000
Does anyone have a definitive understanding of Networker's handling of the
archive bit on Win filesystems ?

My understanding is the default behaviour is to OR the archive bit setting
with
the ctime/mtime of the file for non-fulls, i.e IF (file has been changed
since the
last backup) OR (the archive bit is set) THEN (save the file). It should
then
unset the bit.

However, if NSR_AVOID_ARCHIVE is set to YES, then the archive bit not taken
into account - candidate files are selected purely on ctime/mtime.

The default causes some fun with backups of disk array snapshots, as any
change
to the archive bit is (obviously) not propagated back to the original
filesystem, and
inc/diff backup sizes are artificially large. Files are saved not because
they have
changed, but because the archive bit is set - and it never gets unset on the
production copy of the filesystem.

tia

D
#

----- Original Message -----
From: "Craig Ruefenacht" <craig.ruefenacht AT US.USANA DOT COM>
To: <NETWORKER AT LISTMAIL.TEMPLE DOT EDU>
Sent: Friday, January 23, 2004 4:47 PM
Subject: Re: [Networker] Confusion over incremental and levels - 3 IMPORTANT
questions!


> George,
>
> >From the help file of Networker:
>
> Full - NetWorker backs up every file in the save set,
> no matter when the files last changed.
>
> 1 through 9 - NetWorker backs up only the files that
> have changed since the most recent lower backup level.
> Each backup level is represented by a number, 1 through
> 9, where 1 represents the fullest backup and 9
> represents the most minimal backup.
>
> Incremental - NetWorker backs up files that have
> changed since the previous backup, regardless of the
> level of the previous backup.
>
>
> On Fri, 2004-01-23 at 09:28, George Sinclair wrote:
> > Hi,
> >
> > A user stopped to ask me today what exactly is an incremental. This led
> > to a discussion about levels and such and left me with three questions
> > that I'm uncertain about myself. I explained that an incremental
> > captures all changed files since the previous incremental and so on and
> > so forth. I explained that if you run a full on Monday, then running a
> > level 5, 4, 3, 2, or 1 on Tuesday is tantamount to running an
> > incremental on Tuesday, since the full resets everything, but that's
> > where the buck stops. As long as the client index has room to grow, the
> > incrementals can just keep going and going, each capturing everything
> > since the previous one, but a full will start the process all over again
> > from scratch and levels capture everything since the previous lower
> > numbered level, but do they likewise reset things? The user asked what
> > would happen in the following scenario:
> >
> > 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.
> >
> > 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?
> >
> > 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?
> >
> > Thanks!
> >
> > George
> >
> > --
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email
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> --
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