Re: [Bacula-users] Running out of space on tape

Il 16/04/2012 15:59, Jack Cobb ha scritto:
> Hi,
>
> I am using Bacula 5.0.1 running on an Ubuntu 10.04 64-bit server with a
> Dell PowerVault TL2000 tape library attached via a SAS controller. In
> the library are two LTO4 drives and I am using LTO4 media. From a backup
> over the weekend I found the following message in the bacula log:
>
> utility-sd JobId 377: End of medium on Volume "000032"
> Bytes=843,378,278,400 Blocks=13,073,199 at 14-Apr-2012 19:45
>
> I was hoping to get more than 843GB on a tape that can hold 800GB
> without compression. I guess I can go to two tapes for this backup in
> the future but I would sure hate to spend money on more tapes. Has
> anyone run into a similar situation?
>
> Jack Cobb
>
>
>
> ------------------------------------------------------------------------------
> For Developers, A Lot Can Happen In A Second.
> Boundary is the first to Know...and Tell You.
> Monitor Your Applications in Ultra-Fine Resolution. Try it FREE!
> http://p.sf.net/sfu/Boundary-d2dvs2
>
>
>
> _______________________________________________
> Bacula-users mailing list
> Bacula-users AT lists.sourceforge DOT net
> https://lists.sourceforge.net/lists/listinfo/bacula-users

If the data sent to tape is already compressed there's little that can 
be done by the tape drive to compress it further.
For example, if all you store on the drive are text files, there are 
good chances you'll be able to store more than two times the 
uncompressed tape capacity. On the other side, if you store only jpeg 
images, it will fill up after no more than is native capacity, because 
the jpeg algorithm already eliminates redundand data from images in a 
very domain-specific way (thus any other algorithm can't do much better 
than that).
So the actual size of data that can be stored on a tape depends on the 
level of redundancy of the data itself. In other words, one can only 
make assumptions about the native (i.e. uncompressed) tape capacity.

HTH

-- 
Marcello Romani

------------------------------------------------------------------------------
For Developers, A Lot Can Happen In A Second.
Boundary is the first to Know...and Tell You.
Monitor Your Applications in Ultra-Fine Resolution. Try it FREE!
http://p.sf.net/sfu/Boundary-d2dvs2
_______________________________________________
Bacula-users mailing list
Bacula-users AT lists.sourceforge DOT net
https://lists.sourceforge.net/lists/listinfo/bacula-users