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List:       amanda-users
Subject:    Re: Newbie help
From:       Jon LaBadie <jon () jgcomp ! com>
Date:       2015-12-03 4:15:57
Message-ID: 20151203041557.GA28870 () cyber ! jgcomp ! com
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On Wed, Dec 02, 2015 at 08:35:26PM -0500, Chris Lewis wrote:
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> On 12/02/2015 01:36 PM, Jon LaBadie wrote:
> | On Tue, Dec 01, 2015 at 10:28:27PM +0000, Debra S Baddorf wrote:
> |> I agree with Alan's comment.   You shouldn't need   - - notaper.
> |> (But you CAN use it
> 
> Thanks all, I think I understand now.  It's a bit more subtle than
> understanding Amanda config (which I don't yet!)
> 
> The filesystem to be backed up consists of 9 directories, where almost
> every file is hard-linked into the other 8 directories.
> 
> [It's daily backups and incrementals, where if the file is unchanged,
> it's hard-linked to the other identical copies.]
> 
> While df and du both show the backup to be 990Gb, a naive view (not
> taking into account hard links) shows it at over 7Tb.  The Amanda size
> estimator shows 7Tb (via amstatus), not 990Gb, hence, it's way too big
> for my 1.5Tb holding area.  Web searches on the subject seem to
> indicate that the Amanda backups _will_ preserve hard links (hence
> only backing up 990Gb), so if I let the backup run, it would have
> worked (but shoe-shined unacceptably).  On a faster drive, the
> shoe-shine wouldn't have mattered, but it would have bleated about not
> having enough tapes (even tho it wouldn't use them).
> 

What "estimate" type are you using for your new DLE?

  estimate [ client | calcsize | server ]+

    Default: client.  Determine the way Amanda estimates the size of each DLE
    before beginning a backup.  This is a list of acceptable estimate methods,
    and Amanda applies the first method supported by the application.
    The methods are:

      client

        Use the same program as the dumping program.  This is the most accurate
	method to do estimates, but it can take a long time.

      calcsize

        Use a faster program to do estimates, but the result is less accurate.

      server

        Use only statistics from the previous few runs to give an estimate.
	This very quick, but the result is not accurate if ...

Note the client type estimate will use tar, using the backup options but
dumping to /dev/null, to make the estimate.  As you note the standard tar
options deal with hard links so the estimate should match the actual size.

jl
-- 
Jon H. LaBadie                 jon@jgcomp.com
 11226 South Shore Rd.          (703) 787-0688 (H)
 Reston, VA  20190              (703) 935-6720 (C)
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