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Re: [Bacula-devel] Optimizing disk based backups
On Friday 23 May 2008 20:31:09 Michael Short wrote:
> I realize that Bacula was originally developed for tape based backup
> systems, but disk space is becoming more inexpensive everyday. It is
> cheaper and more reliable to maintain a system which uses disk based
> mediums to store backup data. The problem is that disk based restores
> are unnecessarily slow, due to the linear nature of the backup
You are probably running with an old version of Bacula because disk based
restores even with monster files are lightning fast because they use lseek().
I forget in which version this was implemented, but it seems to me was 2.2.0
> I am addressing this problem because at some point it would be
> necessary to access old backup archives should anyone implement an
> rsync or xdelta type enhancement for Bacula. Perhaps instead of
> storing individual file locations in the catalog,
Bacula does not store individual file locations in the catalog. It stores
what one might call check points or seek points.
> an index of the
> backup could be stored at the beginning or end of a volume,
Bacula already keeps indexes of the backup in the catalog, so there is no need
to store it on the volume.
> so that
> unnecessary "forward spacing" would no longer be needed for disk based
> volumes. This extra would also make the process of recovering catalog
> information from volumes much less painful.
Bacula normally optimizes forward spacing, and on disk volumes (version 2.2.0
and greater) a "forward space" is essentially instantaneous -- no I/O
involved simply an lseek() call. Without "forward spacing" Bacula would be
unable to restore files, so I am not sure I see your point unless you are
using an old Bacula version where it sequentially reads the volume to effect
> Just a suggestion..
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