Eduardo Sieber schrieb:

>
> I Have a bacula verion backup-dir Version: 2.4.4 (28 December 2008)
> i486-pc-linux-gnu debian 5.0, intalled on a Ubuntu 9.1 server. I have 2 tape
> drives attached on this server (A DLT 40/80Gb and a sony SDX470V 40/102 GB).
>
> I've ran btape on both tapes and everything is fine on the test.
>
> So, I have a job, and the estimate command for this job says:
> 000 OK estimate files=94902 bytes=58,095,727,131
>
> Something about 56Gb, that fits on my AIT tape right?
>
>
> So, runing this job, I got this message:
> Please use the "label" command to create a new Volume for:
> Storage: "AIT-1" (/dev/nst0)
> Pool: Semanal
> Media type: AIT-1
> 15-Jul 09:52 backup-sd JobId 8: Job Semanal.2009-07-15_06.51.40.17 waiting.
> Cannot find any appendable volumes.
>
> This way I think: The tape is full and bacula is requesting a new one to
> finish the job. After this, I proceed the command estimate at the Storage
> daemon, and I got:
>
> Running Jobs:
> JobId 8 Job Semanal.2009-07-15_06.51.40.17 is running.
> Backup Job started: 15-Jul-09 15:58
> Files=66,399 Bytes=48,242,126,113 Bytes/sec=845,789 Errors=0
> Files Examined=66,399
> Processing file:
> /samba/Publica/FUUUTBOOOL/FUTEBOL_SDAB/Sdab2_x_PM1/parte_18.MPG
> SDReadSeqNo=5 fd=5
>
> Director connected at: 16-Jul-09 07:48
>
> He writes abut 40GB And get the tape full. But with HW compression it must
> writes 100GB!

No it must no!


DLT = 40/80GB
SDX470V AIT = 40/104GB

native capacity = 40GB
 This should fit on the tape in all cases

maximum compressed capacity = 80GB (DLT), 104 GB (AIT)
 This is the _theoretical_ maximum if your data is not already
 compressed on the data server

You will see the max. capacity only in rare cases. If you have many
zip/mpeg/mp3 files, you will not get anything near the theoretical
maximum.

It always depends on your data....

Quoting wikipedia:

http://en.wikipedia.org/wiki/Digital_Linear_Tape
All (S)DLT drives support hardware data compression. The often-used
compression factor of 2:1 is optimistic and generally only achievable
for text data; a more realistic factor across a file system is 1.3:1
to 1.5:1. Note that drive compression applied to pre-compressed data
can actually make the written data larger than having compression
turned off in the tape drive.



Ralf

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