On Thu, 15 Jul 2010 15:46:38 +0100
Rory Campbell-Lange <rory AT campbell-lange DOT net> wrote:

> We are presently trying to use Amanda to write 7-10TB of data from one
> server to an LTO4 tape library. We are frustrated with problems in
> retrieving files from the second tape onwards. Amanda seems to suffer
> from an intrinsic problem about knowing where to find a file from the
> backup set, which is frustrating the process of resolving this problem
> as the whole backup has to be dumped to disk to try and find the file.
> 
> Consequently we are considering moving to Bacula. The integration with
> Postgres and python sounds very good to us.
> 
> I'd be grateful to know if the Bacula catalogue records allow Bacula to
> more rapidly restore data from large tape sets by understanding which
> tape it is stored upon.
>

Restoring particular files is quite easy in Bacula because that
information is stored in the database.  So it knows where to find which
file on the tapes.  

If the database is not available (e.g. you've pruned the file entries
or your database server failed), then you can scan the tapes and build
the database.  This does take longer and has more steps. 

> I'd also be grateful for comments on how to best deal with an
> environment where the main storage server will act as Bacula Director,
> Client and Storage, and in an environment with only ssh access to a
> shell console.

That is my environment as well, I only use bconsole, and my tape
library is attached to a machine which NFS mounts all of the stuff that
needs to be backed up.  And the database daemon is local there as
well.  The main thing is to have enough hardware performance to handle
the DB workload and the tape streaming, etc.  I have the DB on
dedicated spindles and then also a large spool area where files get
staged before getting written to tape.

> 
> A final question about the on-tape format:
> We chose Amanda originally because we could cite it as using an "open
> standard" which would allow people to easily restore data in 15 years'
> time assuming the tapes hadn't become corrupt. I understand that Bacula
> uses its own tape format and that over time, this has changed.
>

The format is documented and the utilities required to read/write it
are Free Software.  So it's equivalent to, say, GNU tar.


Set it up and try it out!  I think you will find it easier than Amanda.


Regards,
-- 
Alex Chekholko   chekh AT genomics.upenn DOT edu

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