From FAQ Bacula Wiki:
Why is my backup larger than my disk space usage?
The most common culprit of this is having one or more sparse files.
A sparse file is one with large blocks of nothing but zeroes that the operating
system has optimized. Instead of actually storing disk blocks of nothing but
zeroes, the filesystem simply contains a note that from point A to point B, the
file is nothing but zeroes. Only blocks that contain non-zero data are
allocated physical disk blocks.
The single biggest culprit seems to be the contents of /var/log/lastlog on 64
bit systems. Since the lastlog file is extended to preallocate space for all
UIDs, the switch from a 32 bit UID space to a 64 bit UID increases the full
size to over 1TB.
Luckily the fix is simple - turn on sparse file support in the FileSet, will
detect sparse files and not store the zerofill blocks.
Another possible cause is that your fileset accidentally includes some folders
twice. Taken from the manual:
Take special care not to include a directory twice or Bacula will backup
the same files two times wasting a lot of space on your archive device.
Including a directory twice is very easy to do. For example:
Include {
File = /
File = /usr
Options { compression=GZIP }
}
on a Unix system where /usr is a subdirectory (rather than a mounted
filesystem) will cause /usr to be backed up twice.
----- Original Message -----
From: "John Drescher" <drescherjm AT gmail DOT com>
To: "Tilman Schmidt" <t.schmidt AT phoenixsoftware DOT de>
Cc: "bacula-users" <bacula-users AT lists.sourceforge DOT net>
Sent: Sunday, December 18, 2011 10:21:58 AM
Subject: Re: [Bacula-users] amazing backup size
On Sun, Dec 18, 2011 at 9:09 AM, Tilman Schmidt
<t.schmidt AT phoenixsoftware DOT de> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> A newly installed CentOS 6 / Bacula 5 backup server is reporting
> this when backing itself up:
>
> FD Bytes Written: 53,655,908,904 (53.65 GB)
> SD Bytes Written: 53,664,006,577 (53.66 GB)
> Last Volume Bytes: 53,705,852,928 (53.70 GB)
>
> Which is truly amazing because the actual amount of data stored
> on this system is far less than that:
>
> [r2d2@backup ~]$ LANG=C df -h
> Filesystem Size Used Avail Use% Mounted on
> /dev/mapper/vg_backup-lv_root
> 50G 2.2G 45G 5% /
> tmpfs 1.9G 0 1.9G 0% /dev/shm
> /dev/sda1 485M 47M 413M 11% /boot
> /dev/mapper/vg_backup-lv_home
> 174G 2.4G 163G 2% /home
>
> Any explanations for that discrepancy?
>
No, I have never seen anything like this. And this is from a bacula
user for 8+ years who has run tens of thousands of backups for a
department with 50+ machines and 30 to 50TB on tape. I suggest you
examine what bacula has saved in the backup. The simplest way is to
use the bat version browser or the new restore viewer if you have
bacula-5.2.X.
John
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------------------------------------------------------------------------------
Learn Windows Azure Live! Tuesday, Dec 13, 2011
Microsoft is holding a special Learn Windows Azure training event for
developers. It will provide a great way to learn Windows Azure and what it
provides. You can attend the event by watching it streamed LIVE online.
Learn more at http://p.sf.net/sfu/ms-windowsazure
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